i915: restore only the mode of this driver on lastclose

This has always used a big hammer, but that hammer is probably
too big, I'm also not sure its necessary but at least this
should be safe.

Should fix: https://bugzilla.kernel.org/show_bug.cgi?id=23592

Signed-off-by: Dave Airlie <airlied@redhat.com>
3 files changed