drm/nouveau: Resume hotplug interrupts earlier

Currently, we enable hotplug detection only after we re-enable the
display. However, this is too late if we're planning on sending sideband
messages during the resume process - which we'll need to do in order to
reprobe the topology on resume.

So, enable hotplug events before reinitializing the display.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191022023641.8026-11-lyude@redhat.com