exit: remove unneeded declaration of exit_mm()

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/exit.c

@@ -59,8 +59,6 @@
 #include <asm/pgtable.h>
 #include <asm/mmu_context.h>
 
-static void exit_mm(struct task_struct *tsk);
-
 static void __unhash_process(struct task_struct *p, bool group_dead)
 {
 	nr_threads--;