IB/usnic: Add dependency on CONFIG_INET

usNIC needs inet notifiers to function correctly, so add a Kconfig
dependency on CONFIG_INET.
Signed-off-by: Upinder Malhi <umalhi@cisco.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/usnic/Kconfig

 config INFINIBAND_USNIC
 	tristate "Verbs support for Cisco VIC"
-	depends on NETDEVICES && ETHERNET && PCI && INTEL_IOMMU
+	depends on NETDEVICES && ETHERNET && INET && PCI && INTEL_IOMMU
 	select ENIC
 	select NET_VENDOR_CISCO
 	select PCI_IOV