drivers: spi: create Ambiq SPI BLEIF driver

Some Ambiq Apollox Blue SOC (e.g. Apollo3 Blue) uses internal designed
BLEIF module which is different from the general IOM module for SPI
transceiver. The called HAL API will also be independent. This driver is
implemented for the BLEIF module usage scenarios.

Signed-off-by: Aaron Ye <aye@ambiq.com>