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/j721e_evm_a72_defconfig b/configs/j721e_evm_a72_defconfig
index b507f23..c0f55d8 100644
--- a/configs/j721e_evm_a72_defconfig
+++ b/configs/j721e_evm_a72_defconfig
@@ -29,6 +29,7 @@
 # CONFIG_USE_SPL_FIT_GENERATOR is not set
 CONFIG_BOOTCOMMAND="run findfdt; run distro_bootcmd; run init_${boot}; run main_cpsw0_qsgmii_phyinit; run boot_rprocs; run get_kern_${boot}; run get_fdt_${boot}; run get_overlay_${boot}; run run_kern"
 CONFIG_LOGLEVEL=7
+CONFIG_SPL_MAX_SIZE=0xc0000
 CONFIG_SPL_BOARD_INIT=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SPL_STACK_R=y