risc-v/bl808: Add SPI driver

This commit implements a driver for SPI0 and SPI1 on the BL808 and introduces an accompanying example configuration.

Documentation/platforms/risc-v/bl808/boards/ox64/index.rst

@@ -143,3 +143,10 @@ adc
 This configuration enables support for the general purpose ADC and the adc example app.
 By default, the ADC will scan external channels 3, 4, 6, 7 and 9 (GPIO pins 11, 6, 12,
 13 and 18). Serial Console is enabled on UART3 at 2 Mbps.
+
+spi
+---
+
+This configuration enables support for SPI0 and spitool.
+By default, GPIO14 is MISO, 13 is MOSI, 15 is SCLK and 12 is SS.
+Serial Console is enabled on UART3 at 2 Mbps.

Documentation/platforms/risc-v/bl808/index.rst

@@ -51,7 +51,7 @@ GPIO         Yes
 I2C          No
 I2S          No
 PWM          No
-SPI          No
+SPI          Yes
 Timers       No
 UART         Yes
 USB          No