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/omap3_beagle_defconfig b/configs/omap3_beagle_defconfig
index 8a54276..1518d1e 100644
--- a/configs/omap3_beagle_defconfig
+++ b/configs/omap3_beagle_defconfig
@@ -14,6 +14,7 @@
 CONFIG_USE_PREBOOT=y
 CONFIG_DEFAULT_FDT_FILE="omap3-beagle.dtb"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
+CONFIG_SPL_MAX_SIZE=0xec00
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 # CONFIG_SPL_FS_EXT4 is not set
 CONFIG_SPL_MTD_SUPPORT=y