vdpa/mlx5: Fix clearing of VIRTIO_NET_F_MAC feature bit

Cited patch in the fixes tag clears the features bit during reset.
mlx5 vdpa device feature bits are static decided by device capabilities.
These feature bits (including VIRTIO_NET_F_MAC) are initialized during
device addition time.

Clearing features bit in reset callback cleared the VIRTIO_NET_F_MAC. Due
to this, MAC address provided by the device is not honored.

Fix it by not clearing the static feature bits during reset.

Fixes: 0686082d

 ("vdpa: Add reset callback in vdpa_config_ops")
Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20211026175519.87795-7-parav@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>