drm/i915: fixup runtime PM handling v2

drm/i915: fixup runtime PM handling v2

According to the PCI docs and Rafael, we don't need to be doing explicit
enables and disables in our init and teardown routines, as they're taken
care of by the PCI core.  So drop the pm_runtime_disable() at teardown
and pm_runtime_set_active() at init.

This fixes one failure of the basic-pci-d3-state test on my BYT.

v2: drop extra get_noresume() and put_noidle() (Rafael)

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>