[ARM] pxa/em-x270: explicitly set .gpio_cs in TDO35S SPI chip data

After commit a7bb3909 ("spi: pxa2xx_spi:
introduce chipselect GPIO to simplify the common cases") the .gpio_cs
field in pxa2xx_spi_chip has to be set explicitly.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Eric Miao <eric.miao@marvell.com>