linux-phytec-ti

drm/omap: fix plane update warning when crtc is disabled

If omap_plane_atomic_update() is called when the crtc is disabled, and
the timings are zero, we'll see the following warning:

omapdss DISPC error: cannot calculate scaling settings: pclk is zero
omapdrm omapdrm.0: Failed to setup plane vid2

It shouldn't cause any issues, as the crtc is disabled so the plane is
not used by the HW.

To remove the warning, check whether the crtc is enabled at the
beginning of omap_plane_atomic_update(), and bail out if not.

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