Convert CONFIG_SPL_INIT_MINIMAL et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_INIT_MINIMAL
   CONFIG_SPL_FLUSH_IMAGE
   CONFIG_SPL_SKIP_RELOCATE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P1010RDB-PB_NAND_defconfig b/configs/P1010RDB-PB_NAND_defconfig
index 9f839f5..eb0e482 100644
--- a/configs/P1010RDB-PB_NAND_defconfig
+++ b/configs/P1010RDB-PB_NAND_defconfig
@@ -29,6 +29,8 @@
 CONFIG_ID_EEPROM=y
 # CONFIG_SPL_FRAMEWORK is not set
 CONFIG_SPL_NAND_BOOT=y
+CONFIG_SPL_INIT_MINIMAL=y
+CONFIG_SPL_FLUSH_IMAGE=y
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_TPL=y
 CONFIG_TPL_DRIVERS_MISC=y