drivers: video: hdmi: cleanup coding style in video a bit

Eliminate the magic numbers, add vendor infoframe size macro
like other hdmi modules.

Signed-off-by: Bernard Zhao <bernard@vivo.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: opensource.kernel@vivo.com
[b.zolnierkie: add "hdmi" to the patch summary]
[b.zolnierkie: fix "vender" -> vendor" typo in the patch description]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200427080530.3234-1-bernard@vivo.com