drm/vc4: crtc: Deal with different number of pixel per clock

Some of the HDMI pixelvalves in vc5 output two pixels per clock cycle.
Let's put the number of pixel output per clock cycle in the CRTC data and
update the various calculations to reflect that.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/18a3bb079981ba820132b37e736a4bb371234d2e.1599120059.git-series.maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_drv.h

@@ -454,6 +454,9 @@ struct vc4_crtc_data {
 struct vc4_pv_data {
 	struct vc4_crtc_data	base;
 
+	/* Number of pixels output per clock period */
+	u8 pixels_per_clock;
+
 	enum vc4_encoder_type encoder_types[4];
 	const char *debugfs_name;