msm: pcie: output the PCIe log to console

The detailed debugging of PCIe driver is disabled by default. It is
only output to kernel log when we enable it from console for
debugging. Change the logging level from info to alert here, in
order to output all the PCIe log to the serial console and capture
the needed debugging info even if the target crashes. This change
here will not add any more logging to kernel message in the normal
build and will not impact other drivers.

Change-Id: Ie332b82d4b5f352948bce92c648ab9d442fb1772
Signed-off-by: Yan He <yanhe@codeaurora.org>