drm/i915: Check has_infoframes when enabling infoframes

has_infoframe is what tells us whether infoframes should be enabled, so
let's pass that instead of has_hdmi_sink to .set_infoframes().

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170818134958.15502-3-ville.syrjala@linux.intel.com