This string is not NUL terminated.

Fixes the following W=1 kernel build warning(s):

 from drivers/scsi/pm8001/pm8001_sas.c:41:
 In function ‘strncpy’,
 inlined from ‘pm8001_issue_ssp_tmf’ at drivers/scsi/pm8001/pm8001_sas.c:919:2:
 include/linux/string.h:297:30: warning: ‘__builtin_strncpy’ specified bound 8 equals destination size [-Wstringop-truncation]
 297 | #define __underlying_strncpy __builtin_strncpy
 | ^
 include/linux/string.h:307:9: note: in expansion of macro ‘__underlying_strncpy’
 307 | return __underlying_strncpy(p, q, size);
 | ^~~~~~~~~~~~~~~~~~~~

Link: https://lore.kernel.org/r/20201102102544.1018706-2-lee.jones@linaro.org
Cc: Jack Wang <jinpu.wang@cloud.ionos.com>
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>