ARM: dts: msm: Add FAN cooling device to msm8996 CV2X boards

Add a node for a GPIO-based FAN cooling device for msm8996
CV2X boards. This GPIO has a single speed and can be controlled
from user space.

Change-Id: Iee427407f3c4032e1394c61dd1f225e24a091a99
Signed-off-by: Gustavo Solaira <gustavos@codeaurora.org>