microblaze: signal: Declare do_notify_resume

Fix sparse warning by declaration do_notify_resume function
called from entry.S.
Warning:
arch/microblaze/kernel/signal.c:357:6: warning: symbol
'do_notify_resume' was not declared. Should it be static?

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/microblaze/kernel/signal.c b/arch/microblaze/kernel/signal.c
index 3903e3d..ac3d0a0 100644
--- a/arch/microblaze/kernel/signal.c
+++ b/arch/microblaze/kernel/signal.c
@@ -354,7 +354,7 @@
 	restore_saved_sigmask();
 }
 
-void do_notify_resume(struct pt_regs *regs, int in_syscall)
+asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
 {
 	/*
 	 * We want the common case to go fast, which