X6883B supports switching between 60, 90 and 120 Hz refresh rates,
so let's expose it in Settings -> Display -> Peak refresh rate for users to save
battery if necessary.
Test: visual confirmation after toggling several times
Change-Id: Ia206c495e3f40f583f8cd35e7753c30a5e917656
Signed-off-by: dodyirawan85 <40514988+dodyirawan85@users.noreply.github.com>