drm/nouveau/pci: do a msi rearm on init

drm/nouveau/pci: do a msi rearm on init

[ Upstream commit a121027d2747168df0aac0c3da35509eea39f61c ]

On my GP107 when I load nouveau after unloading it, for some reason the
GPU stopped sending or the CPU stopped receiving interrupts if MSI was
enabled.

Doing a rearm once before getting any interrupts fixes this.

Signed-off-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>