linux-phytec-ti

drm/omap: cleanup dispc_mgr_lclk_rate()

With the new PLL helpers, we can clean up the dispc_mgr_lclk_rate().
This will also make dispc_mgr_lclk_rate() support clock sources it
didn't support earlier.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>