bpf: update the comment for BTF_FIELDS_MAX

The commit d56b63c ("bpf: add support for bpf_wq user type")
changes the fields support number to 11, just sync the comment.

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240424054526.8031-1-haiyue.wang@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -184,7 +184,7 @@ struct bpf_map_ops {
 };
 
 enum {
-	/* Support at most 10 fields in a BTF type */
+	/* Support at most 11 fields in a BTF type */
 	BTF_FIELDS_MAX	   = 11,
 };