arm64: remove assembly code string functions

Inconsistent progress was observed running ramstage.
It was determined that the hand-coded assembly functions
were causing issues. Some of the comments seems suspect about
the hardware taking care of alignment. The prudent thing to do
is to use the C ones. Optimization can come later after maturity.

BUG=chrome-os-partner:29923
BRANCH=None
TEST=Built and booted to attempting to payload

Original-Change-Id: I4137adf9b36b638ed207e4efd57adaac64c6a6c1
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/207431
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit 2762e478c6b59dd30c59aa87a922d0f78c00c0c4)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Id3196b0c2bf41a21db31f999ba437d118875a236
Reviewed-on: http://review.coreboot.org/8587
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)

src/arch/arm64/memset.S

@@ -1,52 +0,0 @@
-/*
- * Copyright (C) 2013 ARM Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <arch/asm.h>
-
-/*
- * Fill in the buffer with character c (alignment handled by the hardware)
- *
- * Parameters:
- *	x0 - buf
- *	x1 - c
- *	x2 - n
- * Returns:
- *	x0 - buf
- */
-ENTRY(memset)
-	mov	x4, x0
-	and	w1, w1, #0xff
-	orr	w1, w1, w1, lsl #8
-	orr	w1, w1, w1, lsl #16
-	orr	x1, x1, x1, lsl #32
-	subs	x2, x2, #8
-	b.mi	2f
-1:	str	x1, [x4], #8
-	subs	x2, x2, #8
-	b.pl	1b
-2:	adds	x2, x2, #4
-	b.mi	3f
-	sub	x2, x2, #4
-	str	w1, [x4], #4
-3:	adds	x2, x2, #2
-	b.mi	4f
-	sub	x2, x2, #2
-	strh	w1, [x4], #2
-4:	adds	x2, x2, #1
-	b.mi	5f
-	strb	w1, [x4]
-5:	ret
-ENDPROC(memset)