ARM: dts: keystone: add cell's information to spi nodes

SPI nodes should always have #address-cells and #size-cells defined,
otherwise warnings will be produced in case of adding any child
nodes to the SPI bus in DT:
Warning (avoid_default_addr_size): Relying on default #address-cells value for /soc/spi@21000400/n25q128a11@0
Warning (avoid_default_addr_size): Relying on default #size-cells value for /soc/spi@21000400/n25q128a11@0

Hence, ensure that all SPIx nodes have #address-cells and #size-cells
properties defined.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>