msm: mdss: Replace enums with strings in panel dtsi

To make dtsi files more readable, enums or u32
values that referred to strings in the panel
dtsi files are replaced by strings.

Change-Id: I516358c7027fe9ed05541b56c2de47280a23baab
CRs-Fixed: 511801
Signed-off-by: Casey Piper <cpiper@codeaurora.org>
ARM: dts: msm: correct ssd2080m panel commands and timing

Update ssd2080m panel on/off commands,vertical/horizontal
porch values and timing according to vendor's suggestion

CRs-fixed: 569455
Change-Id: Ia60bb8caf55ebbff96751f6b9706f9ef682428c7
Signed-off-by: Ray Zhang <rayzhang@codeaurora.org>