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/include/arm/arch/asm.h

@@ -23,9 +23,11 @@
 #if defined __arm__
 #  define ARM(x...)	x
 #  define THUMB(x...)
+#  define W(instr)	instr
 #elif defined __thumb__
 #  define ARM(x...)
 #  define THUMB(x...)	x
+#  define W(instr)	instr.w
 #else
 #  error Not in ARM or thumb mode!
 #endif