msm: msi: add support for Synopsys MSI

Propagate Synopsys MSI support from msm-4.14 for PCIe controller
and PCIe MSI driver. Changes support:

	1) QGIC MSI/MSI-X
	2) Synopsys MSI/MSI-X
	3) PCIe controller low power modes with MSI

Change-Id: If7a2e1980233e032325ffec597284b9164162407
Signed-off-by: Tony Truong <truong@codeaurora.org>