arm: Update mem* functions to newer versions

The memcpy/memset/memmove assembly implementations have been taken from
U-Boot, which originally got them from Linux. I turns out that they are
actually not that bad, but they could use an update. This patch pulls in
the current Linux upstream versions of those files, removing some old
U-Boot cruft such as checking whether the two pointers in a memcpy() are
equal (really now?) or side-stepping the R8 register because it was used
for special purposes. It also returns to the good old Linux
ENTRY/ENDPROC macros since we have them now anyway, and straightens out
the W() macro in preparation for unified thumb support.

Change-Id: I138af269b423bef0a237759ac29f1ee58ca206a0
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/182179
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
(cherry picked from commit 777127997bde5785b21d422d0b6eb04c4328b478)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6918
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

payloads/libpayload/arch/arm/memcpy.S

@@ -10,9 +10,8 @@
  *  published by the Free Software Foundation.
  */
 
-#include "assembler.h"
-
-#define W(instr)	instr
+#include <arch/asm.h>
+#include "asmlib.h"
 
 #define LDR1W_SHIFT	0
 #define STR1W_SHIFT	0
@@ -57,12 +56,7 @@
 
 /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
 
-.type memcpy, function
-.globl memcpy
-memcpy:
-
-		cmp	r0, r1
-		moveq	pc, lr
+ENTRY(memcpy)
 
 		enter	r4, lr
 
@@ -242,3 +236,4 @@ memcpy:
 17:		forward_copy_shift	pull=16	push=16
 
 18:		forward_copy_shift	pull=24	push=8
+ENDPROC(memcpy)