mx31pdk: Move CONFIG_SPL_LDSCRIPT to defconfig

As there is only one mx31pdk config file and with upcoming updates to
the Kconfig parsing logic, rather than have an entry in
board/freescale/mx31pdk/Kconfig, move this single setting to the
defconfig file.

Cc: Magnus Lilja <lilja.magnus@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by:  Magnus Lilja <lilja.magnus@gmail.com>
diff --git a/configs/mx31pdk_defconfig b/configs/mx31pdk_defconfig
index ac1dac0..595a1be 100644
--- a/configs/mx31pdk_defconfig
+++ b/configs/mx31pdk_defconfig
@@ -2,6 +2,7 @@
 # CONFIG_SPL_USE_ARCH_MEMCPY is not set
 # CONFIG_SPL_USE_ARCH_MEMSET is not set
 CONFIG_ARCH_MX31=y
+CONFIG_SPL_LDSCRIPT="arch/arm/cpu/u-boot-spl.lds"
 CONFIG_SYS_TEXT_BASE=0x87e00000
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_TARGET_MX31PDK=y