drm/i915/dsi: Execute MIPI_SEQ_TEAR_OFF from intel_dsi_post_disable

For v3+ VBTs we should call MIPI_SEQ_TEAR_OFF before MIPI_SEQ_DISPLAY_OFF,
v2 VBTs do not have MIPI_SEQ_TEAR_OFF so there this is a nop.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1488374106-4949-9-git-send-email-jani.nikula@intel.com