staging: vc04_services: setup DMA and coherent mask

VCHI messages between the CPU and firmware use 32-bit
bus addresses. Explicitly set the DMA mask and coherent
on all platforms.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>