s390/pci: don't log availability events as errors

Availability events are logged in s390dbf in s390dbf/pci_error/hex_ascii
even though they don't indicate an error condition.

They have also become redundant as commit 6526a597

 ("s390/pci: add
simpler s390dbf traces for events") added an s390dbf/pci_msg/sprintf log
entry for availability events which contains all non reserved fields of
struct zpci_ccdf_avail. On the other hand the availability entries in
the error log make it easy to miss actual errors and may even overwrite
error entries if the message buffer wraps.

Thus simply remove the availability events from the error log thereby
establishing the rule that any content in s390dbf/pci_error indicates
some kind of error.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>