PCI: Remove fixed parameter in pci_iov_resource_bar()

pci_iov_resource_bar() always sets its 'pci_bar_type' parameter to
'pci_bar_unknown'.  Drop the parameter and just use 'pci_bar_unknown'
directly in the callers.

No functional change intended.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Chris Wright <chrisw@sous-sol.org>
CC: Yu Zhao <yuzhao@google.com>