drm: edid: Constify connector argument to infoframe functions

drm: edid: Constify connector argument to infoframe functions

The drm_hdmi_avi_infoframe_from_display_mode(),
drm_hdmi_vendor_infoframe_from_display_mode() and
drm_hdmi_avi_infoframe_quant_range() functions take a drm_connector that
they don't modify. Mark it as const.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200526011505.31884-10-laurent.pinchart+renesas@ideasonboard.com