pstore: Remove the messages related to compression failure

Remove the messages indicating compression failure as it will
add to the space during panic path.

Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>