net: ethernet: cavium: Correct Cavium Thunderx NIC driver names accordingly to module name

It was found that ethtool provides unexisting module name while
it queries the specified network device for associated driver
information. Then user tries to unload that module by provided
module name and fails.

This happens because ethtool reads value of DRV_NAME macro,
while module name is defined at the driver's Makefile.

This patch is to correct Cavium CN88xx Thunder NIC driver names
(DRV_NAME macro) 'thunder-nicvf' to 'nicvf' and 'thunder-nic'
to 'nicpf', sync bgx and xcv driver names accordingly to their
module names.

Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>