drm: bridge/dw_hdmi: remove unused 'regmap' struct member

This driver does not make use of regmaps, let's remove this unnecessary
structure member.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

drivers/gpu/drm/bridge/dw_hdmi.c

@@ -123,7 +123,6 @@ struct dw_hdmi {
 	bool phy_enabled;
 	struct drm_display_mode previous_mode;
 
-	struct regmap *regmap;
 	struct i2c_adapter *ddc;
 	void __iomem *regs;