Convert CONFIG_SPL_PAD_TO et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_PAD_TO
   CONFIG_SPL_MAX_SIZE
   CONFIG_TPL_PAD_TO
   CONFIG_TPL_MAX_SIZE

Note that we need to make TPL_MAX_SIZE be hex, and so move and convert the
existing places.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/T1042D4RDB_SDCARD_defconfig b/configs/T1042D4RDB_SDCARD_defconfig
index bd9d1ae..9ee4d2b 100644
--- a/configs/T1042D4RDB_SDCARD_defconfig
+++ b/configs/T1042D4RDB_SDCARD_defconfig
@@ -29,6 +29,8 @@
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_BOARD_EARLY_INIT_R=y
 # CONFIG_SPL_FRAMEWORK is not set
+CONFIG_SPL_MAX_SIZE=0x28000
+CONFIG_SPL_PAD_TO=0x40000
 CONFIG_SPL_MMC_BOOT=y
 CONFIG_SPL_FSL_PBL=y
 CONFIG_SPL_FLUSH_IMAGE=y