msm: pcie: improve link recovery mechanism

The PCIe wakeup IRQ could be fired before the linkdown IRQ is fired
when PCIe link goes down, and also could happen during system
suspend/resume process. Thus, update the link recovery mechanism to
handle those cases.

CRs-fixed: 664003
Change-Id: I6bd6249c4c685b1df885226fb5aae551df4bddb9
Signed-off-by: Yan He <yanhe@codeaurora.org>