configs: Drop '$(ARCH)' usage in CONFIG_SPL_LDSCRIPT

In a few boards we had overridden, intentionally, the value used for
CONFIG_SPL_LDSCRIPT.  However, rather than using the ARCH value (arm)
they used the $(ARCH) variable in make.  This doesn't help really, so
switch to a hard-coded value.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/taurus_defconfig b/configs/taurus_defconfig
index 0399132..19d85f9 100644
--- a/configs/taurus_defconfig
+++ b/configs/taurus_defconfig
@@ -6,7 +6,7 @@
 # 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_SPL_LDSCRIPT="arch/arm/cpu/u-boot-spl.lds"
 CONFIG_SYS_TEXT_BASE=0x21000000
 CONFIG_TARGET_TAURUS=y
 CONFIG_BOARD_TAURUS=y