ARM: 5991/1: Fix regression in restore_user_regs macro

ARMv5T and earlier require that a ldm {}^ instruction is not followed
by an instruction that accesses banked registers. This patch restores
the nop that was lost in commit b86040a5.
Signed-off-by: NAnders Grafström <grfstrm@users.sourceforge.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/entry-header.S

@@ -102,6 +102,8 @@
 	.else
 	ldmdb	sp, {r0 - lr}^			@ get calling r0 - lr
 	.endif
+	mov	r0, r0				@ ARMv5T and earlier require a nop
+						@ after ldm {}^
 	add	sp, sp, #S_FRAME_SIZE - S_PC
 	movs	pc, lr				@ return & move spsr_svc into cpsr
 	.endm