vdpa: Provide interface to read driver features

mainline inclusion
from mainline-v5.17-rc1
commit a64917bc
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a64917bc2e9b1e0aa716b783c4ec879fdd280300



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Provide an interface to read the negotiated features. This is needed
when building the netlink message in vdpa_dev_net_config_fill().

Also fix the implementation of vdpa_dev_net_config_fill() to use the
negotiated features instead of the device features.

To make APIs clearer, make the following name changes to struct
vdpa_config_ops so they better describe their operations:

get_features -> get_device_features
set_features -> set_driver_features

Finally, add get_driver_features to return the negotiated features and
add implementation to all the upstream drivers.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20220105114646.577224-2-elic@nvidia.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Pengyuan Zhao <zhaopengyuan@hisilicon.com>