LU-4629 utils: fix input format specifier error

LU-4629 utils: fix input format specifier error

Width is not specified for 's' conversion specifier. This can result in
an overflow of the buffer provided in arguments of a call to 'sscanf'.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: Ic9f37c19461a28a51bd1a0a1a42685b137773a41
Reviewed-on: http://review.whamcloud.com/10667
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>