drm/i915: Prevent signals from interrupting close()
We neither report any unfinished operations during releasing GEM objects
associated with the file, and even if we did, it is bad form to report
-EINTR from a close().
The root cause of the bug that first showed itself during close is that
we do not do proper live tracking of vma and contexts under full-ppgtt,
but this is useful piece of defensive programming enforcing our
userspace API contract.
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>