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/corvus_defconfig b/configs/corvus_defconfig
index 9b55d9e..1c7bc9e 100644
--- a/configs/corvus_defconfig
+++ b/configs/corvus_defconfig
@@ -30,6 +30,8 @@
 CONFIG_BOOTCOMMAND="nand read 0x70000000 0x200000 0x300000;bootm 0x70000000"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_SPL_MAX_SIZE=0x3000
+CONFIG_SPL_PAD_TO=0x20000
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_SPL_NAND_RAW_ONLY=y