ARM: dts: msm: add FT5336 touch panel device tree for SKUK

Add the touch panel FT5336 DT entries into the MSM8939 SKUK dtsi
file. Add virtual key configuration.

Change-Id: I7e14131015f2e667aff8255237030d7af070cbe2
Signed-off-by: Mao Li <maol@codeaurora.org>