[SCSI] ipr: fix buffer overflow

ipr_cmd_label[] isn't big enough for an eight byte string plus terminator.
Fix by shortening the string to seven bytes.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>