ARM: dts: msm: Add KS8851 device for APQ8084 CDP

Add the device definition and associated GPIO configuration
for the KS8851 SPI Ethernet controller on the APQ8084 CDP
platform.

Change-Id: Ib407a753b0e74c66295a6a279c2321dfb32c14ad
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>