mfd: Use DMA for timberdale's ks8842

This patch defines platform data for the ks8842 int the timberdale
MFD.
The platform data contains DMA channels to be used by the driver.

Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>