virtio-pci library: introduce vp_modern_get_driver_features()

stable inclusion
from stable-v5.14
commit 0140b3d0
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0140b3d07617e71a8d9509776434ced107572fc8



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This patch introduce a helper to get driver/guest features from the
device.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210602021536.39525-3-jasowang@redhat.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Pengyuan Zhao <zhaopengyuan@hisilicon.com>