bpf: Fix sparse warnings in kprobe_multi_resolve_syms

Adding missing __user tags to fix sparse warnings:

kernel/trace/bpf_trace.c:2370:34: warning: incorrect type in argument 2 (different address spaces)
kernel/trace/bpf_trace.c:2370:34:    expected void const [noderef] __user *from
kernel/trace/bpf_trace.c:2370:34:    got void const *usyms
kernel/trace/bpf_trace.c:2376:51: warning: incorrect type in argument 2 (different address spaces)
kernel/trace/bpf_trace.c:2376:51:    expected char const [noderef] __user *src
kernel/trace/bpf_trace.c:2376:51:    got char const *
kernel/trace/bpf_trace.c:2443:49: warning: incorrect type in argument 1 (different address spaces)
kernel/trace/bpf_trace.c:2443:49:    expected void const *usyms
kernel/trace/bpf_trace.c:2443:49:    got void [noderef] __user *[assigned] usyms

Fixes: 0dcac27 ("bpf: Add multi kprobe link")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220330110510.398558-1-jolsa@kernel.org

kernel/trace/bpf_trace.c

@@ -2349,11 +2349,11 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip,
 }
 
 static int
-kprobe_multi_resolve_syms(const void *usyms, u32 cnt,
+kprobe_multi_resolve_syms(const void __user *usyms, u32 cnt,
 			  unsigned long *addrs)
 {
 	unsigned long addr, size;
-	const char **syms;
+	const char __user **syms;
 	int err = -ENOMEM;
 	unsigned int i;
 	char *func;