net/thunderx: manage PCI device mapping for SQS VFs

net/thunderx: manage PCI device mapping for SQS VFs

Since the commit e84ad157b7bc ("pci: unmap resources if probe fails"),
EAL unmaps the PCI device if ethdev probe returns positive or
negative value.

nicvf thunderx PMD needs special treatment for Secondary queue set(SQS)
PCIe VF devices, where, it expects to not unmap or free the memory
without registering the ethdev subsystem.

Enable the same behavior by using RTE_PCI_DRV_KEEP_MAPPED_RES
PCI driver flag.

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>