msm: pcie: formalize the logging output

The logging in PCIe bus driver did not distinguish different PCIe
instances in some places and missed some logging info as well. The
change here adds the needed logging info based on the feedback of
the testing.

Change-Id: Ib1c52f8cc2ffdfb2672161e4a79d299dba7861ed
CRs-fixed: 643320
Signed-off-by: Yan He <yanhe@codeaurora.org>