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/devkit3250_defconfig b/configs/devkit3250_defconfig
index 5b25463..ba9ee13 100644
--- a/configs/devkit3250_defconfig
+++ b/configs/devkit3250_defconfig
@@ -23,6 +23,7 @@
 CONFIG_BOOTCOMMAND="dhcp; tftp ${loadaddr} ${serverip}:${tftpdir}/${bootfile}; tftp ${dtbaddr} ${serverip}:${tftpdir}/devkit3250.dtb; setenv nfsargs ip=dhcp root=/dev/nfs nfsroot=${serverip}:${nfsroot},tcp; setenv bootargs ${bootargs} ${nfsargs} ${userargs}; bootm ${loadaddr} - ${dtbaddr}"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_BOARD_EARLY_INIT_F=y
+CONFIG_SPL_MAX_SIZE=0x20000
 CONFIG_SPL_BOARD_INIT=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SPL_NAND_SUPPORT=y