bpf: Fix helpers ctx struct types in uapi doc

Helpers may operate on two types of ctx structures: user visible ones
(e.g. `struct bpf_sock_ops`) when used in user programs, and kernel ones
(e.g. `struct bpf_sock_ops_kern`) in kernel implementation.

UAPI documentation must refer to only user visible structures.

The patch replaces references to `_kern` structures in BPF helpers
description by corresponding user visible structures.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/uapi/linux/bpf.h

@@ -1361,7 +1361,7 @@ union bpf_attr {
  * 	Return
  * 		0
  *
- * int bpf_setsockopt(struct bpf_sock_ops_kern *bpf_socket, int level, int optname, char *optval, int optlen)
+ * int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
  * 	Description
  * 		Emulate a call to **setsockopt()** on the socket associated to
  * 		*bpf_socket*, which must be a full socket. The *level* at
@@ -1435,7 +1435,7 @@ union bpf_attr {
  * 	Return
  * 		**SK_PASS** on success, or **SK_DROP** on error.
  *
- * int bpf_sock_map_update(struct bpf_sock_ops_kern *skops, struct bpf_map *map, void *key, u64 flags)
+ * int bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
  * 	Description
  * 		Add an entry to, or update a *map* referencing sockets. The
  * 		*skops* is used as a new value for the entry associated to
@@ -1533,7 +1533,7 @@ union bpf_attr {
  * 	Return
  * 		0 on success, or a negative error in case of failure.
  *
- * int bpf_perf_prog_read_value(struct bpf_perf_event_data_kern *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
+ * int bpf_perf_prog_read_value(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
  * 	Description
  * 		For en eBPF program attached to a perf event, retrieve the
  * 		value of the event counter associated to *ctx* and store it in
@@ -1544,7 +1544,7 @@ union bpf_attr {
  * 	Return
  * 		0 on success, or a negative error in case of failure.
  *
- * int bpf_getsockopt(struct bpf_sock_ops_kern *bpf_socket, int level, int optname, char *optval, int optlen)
+ * int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
  * 	Description
  * 		Emulate a call to **getsockopt()** on the socket associated to
  * 		*bpf_socket*, which must be a full socket. The *level* at
@@ -1588,7 +1588,7 @@ union bpf_attr {
  * 	Return
  * 		0
  *
- * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops_kern *bpf_sock, int argval)
+ * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *bpf_sock, int argval)
  * 	Description
  * 		Attempt to set the value of the **bpf_sock_ops_cb_flags** field
  * 		for the full TCP socket associated to *bpf_sock_ops* to
@@ -1721,7 +1721,7 @@ union bpf_attr {
  * 	Return
  * 		0 on success, or a negative error in case of failure.
  *
- * int bpf_bind(struct bpf_sock_addr_kern *ctx, struct sockaddr *addr, int addr_len)
+ * int bpf_bind(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len)
  * 	Description
  * 		Bind the socket associated to *ctx* to the address pointed by
  * 		*addr*, of length *addr_len*. This allows for making outgoing