configs: socfpga: disable EFI and ISO partition types

None of the SoCFPGA platforms will support EFI/ISO partition types that
is needed for DISTRO_DEFAULTS. SoCFPGA bootroom will only support 0xa2
partition type.

This is needed to help limit the size of the SPL to within the 64k limit
that is required for SoCFPGA.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>