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/uniphier_v7_defconfig b/configs/uniphier_v7_defconfig
index b69b2b2..13e208c 100644
--- a/configs/uniphier_v7_defconfig
+++ b/configs/uniphier_v7_defconfig
@@ -16,6 +16,8 @@
 CONFIG_USE_PREBOOT=y
 CONFIG_PREBOOT="env exist ${bootdev}preboot && run ${bootdev}preboot"
 CONFIG_LOGLEVEL=6
+CONFIG_SPL_MAX_SIZE=0x10000
+CONFIG_SPL_PAD_TO=0x20000
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_SPL_NOR_SUPPORT=y
 CONFIG_CMD_CONFIG=y