msm: pcie: add support to get PCIe port PHY sequence from DT

PCIe PHY varies between each chipset. Thus, the port PHY init
sequence on each of these chipsets are also different. Therefore,
add the support to read PCIe port PHY init sequence from devicetree.

Change-Id: I92969b7b59a64018b80470566567887248ced2bd
Signed-off-by: Tony Truong <truong@codeaurora.org>