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/chromebook_kevin_defconfig b/configs/chromebook_kevin_defconfig
index ad6cbca..6a3f3cf 100644
--- a/configs/chromebook_kevin_defconfig
+++ b/configs/chromebook_kevin_defconfig
@@ -27,6 +27,8 @@
 CONFIG_BLOBLIST=y
 CONFIG_BLOBLIST_ADDR=0x100000
 CONFIG_BLOBLIST_SIZE=0x1000
+CONFIG_SPL_MAX_SIZE=0x2e000
+CONFIG_SPL_PAD_TO=0x7f8000
 CONFIG_HANDOFF=y
 # CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
 CONFIG_SPL_STACK_R=y