drm: bridge: dw-hdmi: Add a missing break statement

There was supposed to be a break before the next case statement.

Fixes: def23aa7

 ("drm: bridge: dw-hdmi: Switch to V4L bus format and encodings")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170406052132.GA26605@mwanda