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/zynq_cse_nand_defconfig b/configs/zynq_cse_nand_defconfig
index d21ca55..3800288 100644
--- a/configs/zynq_cse_nand_defconfig
+++ b/configs/zynq_cse_nand_defconfig
@@ -21,6 +21,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 # CONFIG_BOARD_LATE_INIT is not set
 CONFIG_CLOCKS=y
+CONFIG_SPL_MAX_SIZE=0x30000
 CONFIG_SPL_STACK_R=y
 # CONFIG_CMDLINE_EDITING is not set
 # CONFIG_AUTO_COMPLETE is not set