This also avoids compiling in pci_iov support into the kernel if_ixoif the PCI_IOV option is disabled.
- rS320973: Fix kldload of if_ixl without PCI_IOV kernel option.
Buitl module without KERNBUILDDIR set (no PCI_IOV), then with (with
opt_pci_iov.h having #define PCI_IOV 1 in it). The now-conditional files
were only built when PCI_IOV was enabled via opt_pci_iov.h from kernel config.