msm: pcie: remove unnecessary global PCI device table

Having a global PCI device table share between all PCIe ports
is not necessary. There is potential race conditions if required
locks are present. remove the global PCI device table completely
and utilize the bus list for each PCIe port instead.

Change-Id: I48ebc086fcf56e4b9a9496615e4185c3893ae278
Signed-off-by: Tony Truong <truong@codeaurora.org>