virtio-pci: implement No_Soft_Reset bit

virtio-pci: implement No_Soft_Reset bit

In current code, when guest does S3, virtio-gpu are reset due to the
bit No_Soft_Reset is not set. After resetting, the display resources
of virtio-gpu are destroyed, then the display can't come back and only
show blank after resuming.

Implement No_Soft_Reset bit of PCI_PM_CTRL register, then guest can check
this bit, if this bit is set, the devices resetting will not be done, and
then the display can work after resuming.

No_Soft_Reset bit is implemented for all virtio devices, and was tested
only on virtio-gpu device. Set it false by default for safety.

Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
Message-Id: <20240606102205.114671-3-Jiqian.Chen@amd.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>