drivers: mspi: Add ATXP032 NOR flash driver

The ATXP032 is a NOR flash device that supports up to ~100MHz
octal SDR/DDR with 4MB nonvolatile memory.
The device driver uses MSPI bus API and could be used across different
SoC controllers that implement the MSPI bus API.

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