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/C29XPCIE_NAND_defconfig b/configs/C29XPCIE_NAND_defconfig
index 7db345e..1c3f07d 100644
--- a/configs/C29XPCIE_NAND_defconfig
+++ b/configs/C29XPCIE_NAND_defconfig
@@ -1,14 +1,14 @@
 CONFIG_PPC=y
 CONFIG_MPC85xx=y
 CONFIG_TARGET_C29XPCIE=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="C29XPCIE,NAND"
 CONFIG_BOOTDELAY=-1
+CONFIG_SPL=y
+CONFIG_TPL=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_I2C=y