drm: bridge: dw-hdmi: Merge __hdmi_phy_i2c_write and hdmi_phy_i2c_write

The latter is just an int wrapper around the former void function that
unconditionally returns 0. As the return value is never checked, merge
the two functions into one.

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/20170117082910.27023-2-laurent.pinchart+renesas@ideasonboard.com