arm, at91: fix taurus board

since commit: b529993e0222 "spl: add hierarchical defaults for SPL_LDSCRIPT"

taurus board stopped working. Use the ldscript from
arch/arm/cpu/u-boot-spl.lds (as before this patch) fixed it.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

configs/taurus_defconfig

@@ -3,6 +3,7 @@ CONFIG_SPL_SYS_THUMB_BUILD=y
 # CONFIG_SPL_USE_ARCH_MEMCPY is not set
 # CONFIG_SPL_USE_ARCH_MEMSET is not set
 CONFIG_ARCH_AT91=y
+CONFIG_SPL_LDSCRIPT="arch/$(ARCH)/cpu/u-boot-spl.lds"
 CONFIG_TARGET_TAURUS=y
 CONFIG_SPL_GPIO_SUPPORT=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y