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/am43xx_hs_evm_defconfig b/configs/am43xx_hs_evm_defconfig
index 33b008f..6b08ebe 100644
--- a/configs/am43xx_hs_evm_defconfig
+++ b/configs/am43xx_hs_evm_defconfig
@@ -22,6 +22,7 @@
 CONFIG_BOOTCOMMAND="run findfdt; run finduuid; run distro_bootcmd"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 # CONFIG_MISC_INIT_R is not set
+CONFIG_SPL_MAX_SIZE=0x36100
 CONFIG_SPL_ETH=y
 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME="u-boot.img"
 CONFIG_SPL_MTD_SUPPORT=y