[ARM] Remove RETINSTR macro

RETINSTR is a left-over from the days when we had 26-bit and
32-bit CPU support integrated into the same tree.  Since this
is no longer the case, we can now remove RETINSTR.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
index a1795f59..69e7c31 100644
--- a/arch/arm/lib/memset.S
+++ b/arch/arm/lib/memset.S
@@ -77,4 +77,4 @@
 	strneb	r1, [r0], #1
 	tst	r2, #1
 	strneb	r1, [r0], #1
-	RETINSTR(mov,pc,lr)
+	mov	pc, lr