arm: fixloop(): do not use r8 for relocation

r8 is used for global_data and should therefore be left alone!

For C code the compiler flag --fixed-r8 does the job, but in assembler
we need to be aware of that fact.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
index df17fe3..d14a7bb 100644
--- a/arch/arm/cpu/arm1136/start.S
+++ b/arch/arm/cpu/arm1136/start.S
@@ -222,10 +222,10 @@
 	ldr	r0, [r2]		/* r0 <- location to fix up, IN FLASH! */
 	add	r0, r0, r9		/* r0 <- location to fix up in RAM */
 	ldr	r1, [r2, #4]
-	and	r8, r1, #0xff
-	cmp	r8, #23			/* relative fixup? */
+	and	r7, r1, #0xff
+	cmp	r7, #23			/* relative fixup? */
 	beq	fixrel
-	cmp	r8, #2			/* absolute fixup? */
+	cmp	r7, #2			/* absolute fixup? */
 	beq	fixabs
 	/* ignore unknown type of fixup */
 	b	fixnext