video: dw_hdmi: fix HSYNC and VSYNC polarity settings

Currently dw_hdmi configures HSYNC polarity using VSYNC setting from
EDID and vice versa. Fix it, since it breaks displays where HSYNC
and VSYNC polarity differs

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>