arm64: dts: exynosautov920: Add DT node for all SPI ports

Universal Serial Interface (USI) supports three serial protocol
like uart, i2c and spi. ExynosAutov920 has 18 instances of USI.
Add spi nodes for all the instances.

Signed-off-by: Faraz Ata <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Krzysztof Kozlowski <[email protected]>

Author: Faraz Ata