MIPS: BMIPS: Enable PCI Kconfig

Enable HAVE_PCI and PCI_DRIVERS_GENERIC so we can build PCIE_BRCMSTB
which is the PCIe host bridge driver for this platform.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>