panel: add support for setting frame rate

Add a new sysfs node and panel function to set the current frame
rate for panels that suppport this feature.

Bug: 346461765
Change-Id: I4b239c305ae0a5d7f7380b8ff3b0dad9a6f3a19c
Merged-In: I4b239c305ae0a5d7f7380b8ff3b0dad9a6f3a19c
Signed-off-by: Jeremy DeHaan <jdehaan@google.com>
(cherry picked from commit ade4edc7349d9eb718f1d8780dbb72070e4590de)
3 files changed