RFBI drivers requires configuration of the update area. Since we don't support
partial updates, the size to be configures is the panel size itself.

Add a timings field in RFBI's driver data. Apart from x_res and y_res, all the
other fields are configured to an initial value when RFBI is enabled. A panel
driver is expected to call omapdss_rfbi_set_size() configure the size of the
panel.
Signed-off-by: NArchit Taneja <archit@ti.com>