net: cavium: Add fine-granular dependencies on PCI

Add dependencies on PCI where necessary.

Fixes: 7e2bc7fb ("net: cavium: Drop dependency of NET_VENDOR_CAVIUM on PCI")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>