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/openpiton_riscv64_spl_defconfig b/configs/openpiton_riscv64_spl_defconfig
index 6e4e454..fdb34d9 100644
--- a/configs/openpiton_riscv64_spl_defconfig
+++ b/configs/openpiton_riscv64_spl_defconfig
@@ -20,6 +20,7 @@
 # CONFIG_ARCH_FIXUP_FDT_MEMORY is not set
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="fdt addr ${fdtcontroladdr}; fdt move ${fdtcontroladdr} ${fdt_addr_r}; load mmc ${mmcdev}:${mmcpart} ${kernel_addr_r} ${image}; booti ${kernel_addr_r} - ${fdt_addr_r}; "
+CONFIG_SPL_MAX_SIZE=0x100000
 # CONFIG_SPL_LEGACY_IMAGE_FORMAT is not set
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 # CONFIG_SPL_BANNER_PRINT is not set