PCI/AER: Add TLP header information to tracepoint

When a PCIe AER error occurs, the TLP header information is printed in the
kernel message but it is missing from the tracepoint.  A userspace program
can use this information in the tracepoint to better analyze problems.

To enable the tracepoint:

  echo 1 > /sys/kernel/debug/tracing/events/ras/aer_event/enable

Example tracepoint output:

  $ cat /sys/kernel/debug/tracing/trace
  aer_event: 0000:01:00.0
  PCIe Bus Error: severity=Uncorrected, non-fatal, Completer Abort
  TLP Header={0x0,0x1,0x2,0x3}

Signed-off-by: Thomas Tai <thomas.tai@oracle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>