drivers: spi: Add basic support for PL022

Add fundamental feature support for PL022 SPI peripheral.
This commit implements synchronous transfer with 8bit-MSB format.

Optional functions are not currently implemented yet.

- interrupt based transfer is not implemented yet.
- DMA transfer is not implemented yet.
- Slave mode is not implemented yet.
- Currently support only 8-bit data transfer.

Hardware limitation:

- LSB-first format is not supported by hardware.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@fujitsu.com>