Kconfig: Move SPL settings into their own file

Move the SPL settings into common/spl where most of the SPL code is kept.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/P1010RDB-PB_36BIT_NAND_defconfig b/configs/P1010RDB-PB_36BIT_NAND_defconfig
index 3056310..c5ae6c6 100644
--- a/configs/P1010RDB-PB_36BIT_NAND_defconfig
+++ b/configs/P1010RDB-PB_36BIT_NAND_defconfig
@@ -2,14 +2,14 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_P1010RDB=y
 CONFIG_PHYS_64BIT=y
-CONFIG_SPL=y
-CONFIG_TPL=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_SYS_EXTRA_OPTIONS="P1010RDB_PB,NAND"
 CONFIG_BOOTDELAY=10
+CONFIG_SPL=y
+CONFIG_TPL=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_SF=y