ARM: dts: msm: adjust virtual key map for msm8937 qrd sku1

The virtual keys KEY_MENU/HOME/KEY_BACK are incorrectly defined
for msm8937 qrd sku1. Exchange the positions of these three virtual
keys for a correct operation of the device.

Change-Id: Id4be499617187d9109ec68694e9d90e0a03068f4
Signed-off-by: Mao Li <maol@codeaurora.org>