arm64: defconfig: enable Intel's eASIC N5X SoCFPGA and Keem Bay SoC

Enable in defconfig two Intel ARM64 architectures: the eASIC N5X SoCFPGA
and Keem Bay SoC.  This allows compile coverage when building default
config.

For the N5X (and Agilex) enable also DesignWare SPI controller in MMIO.

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