[PATCH] ARM: OMAP: Input: ads7846: select correct SPI mode

The device is using a protocoll where writes are on the falling, reads are
on the rising edge of the clock. This maps to SPI mode 1.

Signed-off-by: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>