msm: pcie: move Synopsys MSI support to MSI controller

Remove all Synopsys MSI code in PCIe root complex driver
and call MSI driver to configure and enable the interrupts.

Change-Id: Id7bfef638f08eb266c108e7bb9c752633c3dca0f
Signed-off-by: Tony Truong <truong@codeaurora.org>