drm/i915: Catch yet another unconditioal clflush

Replace the unconditional clflush() with drm_clflush_virt_range()
which does the wbinvd() fallback when clflush is not available.

This time no justification is given for the clflush in the
offending commit.

Cc: stable@vger.kernel.org
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: 2c8ab333

 ("drm/i915: Pin timeline map after first timeline pin, v4.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211014090941.12159-4-ville.syrjala@linux.intel.com
Reviewed-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 9ced1218

)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>