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/sama5d2_xplained_emmc_defconfig b/configs/sama5d2_xplained_emmc_defconfig
index 3af5145..12ad0a4 100644
--- a/configs/sama5d2_xplained_emmc_defconfig
+++ b/configs/sama5d2_xplained_emmc_defconfig
@@ -31,6 +31,7 @@
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="fatload mmc 0:1 0x22000000 at91-sama5d2_xplained.dtb; fatload mmc 0:1 0x23000000 zImage; bootz 0x23000000 - 0x22000000"
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_SPL_MAX_SIZE=0x10000
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_CBSIZE=256
 CONFIG_SYS_PBSIZE=276