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-PA_36BIT_NOR_defconfig b/configs/P1010RDB-PA_36BIT_NOR_defconfig
index 6ded156..0c1cd2f 100644
--- a/configs/P1010RDB-PA_36BIT_NOR_defconfig
+++ b/configs/P1010RDB-PA_36BIT_NOR_defconfig
@@ -20,6 +20,7 @@
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_BOARD_EARLY_INIT_R=y
+CONFIG_SPL_FLUSH_IMAGE=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PBSIZE=276
 CONFIG_CMD_IMLS=y