Allow PCI support for Dove to be disabled.  Some platforms do not have
anything connected to the PCIe ports, so requiring PCI support to be
built into the kernel just wastes space, and presents a lot more config
options than are necessary.

However, select USB_ARCH_HAS_EHCI so that we can still have EHCI
support.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>