msm: mdss: Fix panel ESD detection mode selection

Panel ESD detection supports few different methods, and should determine
the detection mode before checking the correct DT value. This change
make sure BTA and TE detection mode does not need to care for REG read
DT settings.

CRs-Fixed: 1035341
Change-Id: Ib3070f739571fa73684a9c88c35d9af42bca9850
Signed-off-by: Benjamin Chan <bkchan@codeaurora.org>
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>