PCI: qcom: Add Qualcomm PCIe controller driver

The PCIe driver reuses the Designware common code for host and MSI
initialization, and also programs the Qualcomm application specific
registers.

[bhelgaas: remove COMPILE_TEST Kconfig dependency]
Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>