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/Sinovoip_BPI_M3_defconfig b/configs/Sinovoip_BPI_M3_defconfig
index 77b0525..a9c7fc1 100644
--- a/configs/Sinovoip_BPI_M3_defconfig
+++ b/configs/Sinovoip_BPI_M3_defconfig
@@ -13,8 +13,8 @@
 CONFIG_AXP_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="sun8i-a83t-sinovoip-bpi-m3"
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
-CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="SATAPWR=SUNXI_GPD(25)"
+CONFIG_SPL=y
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 # CONFIG_CMD_FPGA is not set