devlink: Add new "enable_vnet" generic device param

Add new device generic parameter to enable/disable creation of
VDPA net auxiliary device and associated device functionality
in the devlink instance.

User who prefers to disable such functionality can disable it using below
example.

$ devlink dev param set pci/0000:06:00.0 \
name enable_vnet value false cmode driverinit
$ devlink dev reload pci/0000:06:00.0

At this point devlink instance do not create auxiliary device for the
VDPA net functionality.

Signed-off-by: Parav Pandit <[e-mail]>
Reviewed-by: Jiri Pirko <[e-mail]>
Reviewed-by: Leon Romanovsky <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/devlink/devlink-params.rst

···
      - Boolean
      - When enabled, the device driver will instantiate RDMA specific
        auxiliary device of the devlink device.
+   * - ``enable_vnet``
+     - Boolean
+     - When enabled, the device driver will instantiate VDPA networking
+       specific auxiliary device of the devlink device.
    * - ``internal_err_reset``
      - Boolean
      - When enabled, the device driver will reset the device on internal

include/net/devlink.h

···
 	DEVLINK_PARAM_GENERIC_ID_ENABLE_REMOTE_DEV_RESET,
 	DEVLINK_PARAM_GENERIC_ID_ENABLE_ETH,
 	DEVLINK_PARAM_GENERIC_ID_ENABLE_RDMA,
+	DEVLINK_PARAM_GENERIC_ID_ENABLE_VNET,
 
 	/* add new param generic ids above here*/
 	__DEVLINK_PARAM_GENERIC_ID_MAX,
···
 
 #define DEVLINK_PARAM_GENERIC_ENABLE_RDMA_NAME "enable_rdma"
 #define DEVLINK_PARAM_GENERIC_ENABLE_RDMA_TYPE DEVLINK_PARAM_TYPE_BOOL
+
+#define DEVLINK_PARAM_GENERIC_ENABLE_VNET_NAME "enable_vnet"
+#define DEVLINK_PARAM_GENERIC_ENABLE_VNET_TYPE DEVLINK_PARAM_TYPE_BOOL
 
 #define DEVLINK_PARAM_GENERIC(_id, _cmodes, _get, _set, _validate)	\
 {									\

net/core/devlink.c

···
 		.name = DEVLINK_PARAM_GENERIC_ENABLE_RDMA_NAME,
 		.type = DEVLINK_PARAM_GENERIC_ENABLE_RDMA_TYPE,
 	},
+	{
+		.id = DEVLINK_PARAM_GENERIC_ID_ENABLE_VNET,
+		.name = DEVLINK_PARAM_GENERIC_ENABLE_VNET_NAME,
+		.type = DEVLINK_PARAM_GENERIC_ENABLE_VNET_TYPE,
+	},
 };
 
 static int devlink_param_generic_verify(const struct devlink_param *param)