This commit implements features provisioning for ifcvf, that means:
1)checkk whether the provisioned features are supported by
the management device
2)vDPA device only presents selected feature bits

Examples:
a)The management device supported features:
$ vdpa mgmtdev show pci/0000:01:00.5
pci/0000:01:00.5:
  supported_classes net
  max_supported_vqs 9
  dev_features MTU MAC MRG_RXBUF CTRL_VQ MQ ANY_LAYOUT VERSION_1 ACCESS_PLATFORM

b)Provision a vDPA device with all supported features:
$ vdpa dev add name vdpa0 mgmtdev pci/0000:01:00.5
$ vdpa/vdpa dev config show vdpa0
vdpa0: mac 00:e8:ca:11:be:05 link up link_announce false max_vq_pairs 4 mtu 1500
  negotiated_features MRG_RXBUF CTRL_VQ MQ VERSION_1 ACCESS_PLATFORM

c)Provision a vDPA device with a subset of the supported features:
$ vdpa dev add name vdpa0 mgmtdev pci/0000:01:00.5 device_features 0x300020020
$ vdpa dev config show vdpa0
mac 00:e8:ca:11:be:05 link up link_announce false
  negotiated_features CTRL_VQ VERSION_1 ACCESS_PLATFORM
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Message-Id: <20221125145724.1129962-13-lingshan.zhu@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>