msm: pcie: Add PCIe features for APQ8084

This change adds PCIe Root Complex features on APQ8084 as follows.
1> New power-on sequence of PCIe core and PHY on 8084.
2> Support new PCIe PHY.
3> Use device tree for PCIe Root Complex.
4> Update the suspend/resume functions.
5> Support multiple controllers.

Change-Id: I9d71485cf736f732611e97300b299520d38fe7f6
Signed-off-by: Yan He <yanhe@codeaurora.org>