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/zc5202_defconfig b/configs/zc5202_defconfig
index cd5cd73..ec0c42b 100644
--- a/configs/zc5202_defconfig
+++ b/configs/zc5202_defconfig
@@ -1,9 +1,9 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MX6=y
 CONFIG_TARGET_ZC5202=y
-CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg,MX6Q"
 CONFIG_BOOTDELAY=3
+CONFIG_SPL=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_I2C=y