armv8: prevent using THUMB

The predominantely 32-bit ARM targets try to compile the SPL in Thumb
mode to reduce code size.
The 64-bit AArch64 instruction set does not know an alternative, concise
encoding, so the Thumb build option should only be set for 32-bit
targets.
Likewise -marm machine options are only valid for ARMv7 targets.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>

arch/arm/lib/Makefile

@@ -77,8 +77,10 @@ ifndef CONFIG_HAS_THUMB2
 
 # for C files, just apend -marm, which will override previous -mthumb*
 
+ifndef CONFIG_ARM64
 CFLAGS_cache.o := -marm
 CFLAGS_cache-cp15.o := -marm
+endif
 
 # For .S, drop -mthumb* and other thumb-related options.
 # CFLAGS_REMOVE_* would not have an effet, so AFLAGS_REMOVE_*

include/configs/sunxi-common.h

@@ -35,7 +35,7 @@
 /*
  * High Level Configuration Options
  */
-#ifdef CONFIG_SPL_BUILD
+#if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_ARM64)
 #define CONFIG_SYS_THUMB_BUILD	/* Thumbs mode to save space in SPL */
 #endif