drm/sun4i: Make COEF_RDY conditional

The COEF_RDY bit isn't found in all the SoCs featuring some variant of the
frontend.

Add it to our quirks structure.
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190118145133.21281-21-paul.kocialkowski@bootlin.com

drivers/gpu/drm/sun4i/sun4i_frontend.c

@@ -96,6 +96,7 @@ static void sun4i_frontend_scaler_init(struct sun4i_frontend *frontend)
 			     sun4i_frontend_vert_coef[i]);
 	}
 
+	if (frontend->data->has_coef_rdy)
 		regmap_write_bits(frontend->regs,
 				  SUN4I_FRONTEND_FRM_CTRL_REG,
 				  SUN4I_FRONTEND_FRM_CTRL_COEF_RDY,

drivers/gpu/drm/sun4i/sun4i_frontend.h

@@ -114,6 +114,7 @@ struct reset_control;
 
 struct sun4i_frontend_data {
 	bool	has_coef_access_ctrl;
+	bool	has_coef_rdy;
 };
 
 struct sun4i_frontend {