spi_imx: Fix misspelled configuration variable SOC_IMX31

This fix a kernel NULL pointer error while initialising SPI introduced
by: 4d2f13be1e370a670c1cae20c194d5ce961e0fa5

Signed-off-by: Alberto Panizzo <alberto@amarulasolutions.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
1 file changed