sh: TS_RESTORE_SIGMASK conversion.

Replace TIF_RESTORE_SIGMASK with TS_RESTORE_SIGMASK and define our own
set_restore_sigmask() function.  This saves the costly SMP-safe set_bit
operation, which we do not need for the sigmask flag since TIF_SIGPENDING
always has to be set too.

Based on the x86 and powerpc change.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index 3eb8493..f0abd58 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -133,7 +133,7 @@
 	! r8: current_thread_info
 	! t:  result of "tst	#_TIF_NEED_RESCHED, r0"
 	bf/s	work_resched
-	 tst	#(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0
+	 tst	#_TIF_SIGPENDING, r0
 work_notifysig:
 	bt/s	__restore_all
 	 mov	r15, r4