drm: bridge: dw-hdmi: Remove PHY configuration resolution parameter

The current code hard codes the call of hdmi_phy_configure() to be 8bpp
and provides extraneous error checking to verify that this hardcoded
value is correct. Simplify the implementation by removing the argument.

Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170117082910.27023-12-laurent.pinchart+renesas@ideasonboard.com