drm/i915: Trim delays for wedging

CI still reports the occasional multi-second delay for resets, in
particular along the wedge+recovery paths. As the likely, and unbounded,
delay here is from sync_rcu, use the expedited variant instead.

Testcase: igt/gem_eio/unwedge-stress
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190219122215.8941-7-chris@chris-wilson.co.uk