x86: Enable PCIe controller on quark/galileo

x86: Enable PCIe controller on quark/galileo

Quark SoC holds the PCIe controller in reset following a power on.
U-Boot needs to release the PCIe controller from reset. The PCIe
controller (D23:F0/F1) will not be visible in PCI configuration
space and any access to its PCI configuration registers will cause
system hang while it is held in reset.

Enable PCIe controller per Quark firmware writer guide.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>