staging/vc04_services: Use correct cache line size

Use the compatible string in the DTB to select the correct cache line
size for the SoC - 32 for BCM2835, and 64 for BCM2836 and BCM2837.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>