vlib: add functions to dynamically open/close PCI device

Old code was only allowing PCIdevices to be scanned during startup,
now driver can open and close device without restart of vpp.

Change-Id: I1a06511e3f16f896101b43dac2bad420b6e6c35e
Signed-off-by: Damjan Marion <damarion@cisco.com>

src/vlib/pci/pci.h

@@ -249,6 +249,11 @@ vlib_pci_bus_master_enable (vlib_pci_dev_handle_t h)
   return vlib_pci_write_config_u16 (h, 4, &command);
 }
 
+clib_error_t *vlib_pci_device_open (vlib_pci_addr_t * addr,
+				    pci_device_id_t ids[],
+				    vlib_pci_dev_handle_t * handle);
+void vlib_pci_device_close (vlib_pci_dev_handle_t h);
+
 clib_error_t *vlib_pci_map_region (vlib_pci_dev_handle_t h, u32 resource,
 				   void **result);