disp: msm: dsi: Config panel test pin to input mode when panel off

The pin was configured to input mode when panel on. But
if continuous splash was on, driver will not power on panel
when booting up, the first time panel off, this gpio was
the default mode or the UEFI config mode.

Change-Id: Ib352343848ab38cab828cc10388b366aeac8905d
Signed-off-by: Yuan Zhao <yzhao@codeaurora.org>