drivers: mspi: shroud controller specifics and fix potential issue

1. Moved ambiq specific macro to mspi_ambiq header.
2. Always fill rx&tx dummy settings regardless of transfer direction.
3. Add the CONFIG_MSPI_* macro for optional features.
4. Fixed the ID read process and add k_sleep during busy_wait in
   atxp032 driver.

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