drm: dw-hdmi-i2s: add missing company name on Copyright

This driver's Copyright is under Renesas Solutions Corp.
This patch updates the year, because this driver was moved
into synopsys folder in 2017.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/87tw1khvnq.wl%kuninori.morimoto.gx@renesas.com