ARM: entry: prefetch/data abort helpers: avoid corrupting r4

Replace r4 with ip for calling abort helpers - ip is allowed to be
corrupted by called functions in the ABI, so it makes more sense to
use such a register.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/entry-armv.S

@@ -47,9 +47,9 @@
 	.macro	pabt_helper
 	mov	r0, r2			@ pass address of aborted instruction.
 #ifdef MULTI_PABORT
-	ldr	r4, .LCprocfns
+	ldr	ip, .LCprocfns
 	mov	lr, pc
-	ldr	pc, [r4, #PROCESSOR_PABT_FUNC]
+	ldr	pc, [ip, #PROCESSOR_PABT_FUNC]
 #else
 	bl	CPU_PABORT_HANDLER
 #endif
@@ -67,9 +67,9 @@
 	@ the fault status register in r1.  r9 must be preserved.
 	@
 #ifdef MULTI_DABORT
-	ldr	r4, .LCprocfns
+	ldr	ip, .LCprocfns
 	mov	lr, pc
-	ldr	pc, [r4, #PROCESSOR_DABT_FUNC]
+	ldr	pc, [ip, #PROCESSOR_DABT_FUNC]
 #else
 	bl	CPU_DABORT_HANDLER
 #endif