PCI: Add Kconfig PCI_IOV dependency for PCI_REALLOC_ENABLE_AUTO

Ensure only valid Kconfig configurations for PCI_REALLOC_ENABLE_AUTO. This
is done by selecting PCI_IOV, which is required by PCI_REALLOC_ENABLE_AUTO
to work.

Signed-off-by: Sascha El-Sharkawy <elscha@sse.uni-hildesheim.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>