drm/rockchip: inno_hdmi: Remove useless copy of drm_display_mode

The driver maintains a copy of the adjusted mode but doesn't use it
anywhere. Remove it.
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Alex Bee <knaerzche@gmail.com>
Signed-off-by: Alex Bee <knaerzche@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20231222174220.55249-6-knaerzche@gmail.com

drivers/gpu/drm/rockchip/inno_hdmi.c

@@ -61,7 +61,6 @@ struct inno_hdmi {
 	unsigned int tmds_rate;
 
 	struct hdmi_data_info	hdmi_data;
-	struct drm_display_mode previous_mode;
 };
 
 static struct inno_hdmi *encoder_to_inno_hdmi(struct drm_encoder *encoder)
@@ -497,9 +496,6 @@ static void inno_hdmi_encoder_mode_set(struct drm_encoder *encoder,
 	struct inno_hdmi *hdmi = encoder_to_inno_hdmi(encoder);
 
 	inno_hdmi_setup(hdmi, adj_mode);
-
-	/* Store the display mode for plugin/DPMS poweron events */
-	drm_mode_copy(&hdmi->previous_mode, adj_mode);
 }
 
 static void inno_hdmi_encoder_enable(struct drm_encoder *encoder)