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/ls2088ardb_tfa_defconfig b/configs/ls2088ardb_tfa_defconfig
index 37d3275..0d91221 100644
--- a/configs/ls2088ardb_tfa_defconfig
+++ b/configs/ls2088ardb_tfa_defconfig
@@ -35,6 +35,7 @@
 CONFIG_BOOTARGS="console=ttyS1,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0600 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256"
 CONFIG_MISC_INIT_R=y
 CONFIG_RESET_PHY_R=y
+CONFIG_SPL_MAX_SIZE=0x16000
 CONFIG_SYS_MAXARGS=64
 CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_IMLS=y