kernel/kallsyms.c: fix double return

Commit 6dd06c9f ("module: make
module_address_lookup safe") introduced double returns in the function
kallsyms_lookup(), it's weird.  The second one should be removed.
Signed-off-by: WANG Cong <wangcong@zeuux.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kallsyms.c

@@ -260,7 +260,6 @@ const char *kallsyms_lookup(unsigned long addr,
 	/* see if it's in a module */
 	return module_address_lookup(addr, symbolsize, offset, modname,
 				     namebuf);
-	return NULL;
 }
 
 int lookup_symbol_name(unsigned long addr, char *symname)