mm/process_vm_access.c: mark function as static

Mark function as static in process_vm_access.c because it is not used
outside this file.

This eliminates the following warning in mm/process_vm_access.c:

  mm/process_vm_access.c:416:1: warning: no previous prototype for `compat_process_vm_rw' [-Wmissing-prototypes]

[akpm@linux-foundation.org: remove unneeded asmlinkage - compat_process_vm_rw isn't referenced from asm]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/process_vm_access.c

@@ -412,7 +412,7 @@ SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
 
 #ifdef CONFIG_COMPAT
 
-asmlinkage ssize_t
+static ssize_t
 compat_process_vm_rw(compat_pid_t pid,
 		     const struct compat_iovec __user *lvec,
 		     unsigned long liovcnt,