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/sama5d27_som1_ek_mmc1_defconfig b/configs/sama5d27_som1_ek_mmc1_defconfig
index b4c8863..4a72c7e 100644
--- a/configs/sama5d27_som1_ek_mmc1_defconfig
+++ b/configs/sama5d27_som1_ek_mmc1_defconfig
@@ -32,6 +32,7 @@
 CONFIG_BOOTCOMMAND="fatload mmc 1 0x22000000 at91-sama5d27_som1_ek.dtb; fatload mmc 1 0x23000000 zImage; bootz 0x23000000 - 0x22000000"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_MISC_INIT_R=y
+CONFIG_SPL_MAX_SIZE=0x10000
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_CBSIZE=256
 CONFIG_SYS_PBSIZE=276