drivers: memc: Add APS6404L device driver

The APS6404L psram is a quad SDR SPI device that runs up to 100MHz.
It can provide 8MB of external RAM for SoCs that supports XIP feature.
The device driver uses MSPI bus API and could be used across
different controllers that implement the MSPI bus API.

Signed-off-by: Swift Tian <swift.tian@ambiq.com>