ARM: omapl138_lcdk: Separate BSS in SPL

In preparation to use full device tree support, SPL can separate
BSS from text region.

This patch enables SPL_SEPARATE_BSS.
Signed-off-by: NAdam Ford <aford173@gmail.com>
Tested-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>

configs/omapl138_lcdk_defconfig

@@ -21,6 +21,7 @@ CONFIG_VERSION_VARIABLE=y
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
+CONFIG_SPL_SEPARATE_BSS=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0xb5
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_HUSH_PARSER=y