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_spiflash_defconfig b/configs/sama5d2_xplained_spiflash_defconfig
index 4981a8a..e494893 100644
--- a/configs/sama5d2_xplained_spiflash_defconfig
+++ b/configs/sama5d2_xplained_spiflash_defconfig
@@ -35,6 +35,7 @@
 CONFIG_BOOTCOMMAND="ext4load mmc 0:1 0x22000000 /boot/at91-sama5d2_xplained.dtb; ext4load mmc 0:1 0x23000000 /boot/zImage; bootz 0x23000000 - 0x22000000"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_MISC_INIT_R=y
+CONFIG_SPL_MAX_SIZE=0x10000
 CONFIG_SPL_DM_SPI_FLASH=y
 CONFIG_SPL_SPI_LOAD=y
 CONFIG_SYS_SPI_U_BOOT_OFFS=0x10000