nouveau: move the hotplug ignore to correct place.

Introduced in b440bde7, however it was added to
the wrong function in nouveau.

https://bugzilla.kernel.org/show_bug.cgi?id=86011


Cc: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org  # v3.15+
Signed-off-by: Dave Airlie <airlied@redhat.com>