tests: Change FAT volume label to be with in the valid character range

tests: Change FAT volume label to be with in the valid character range

The ";", semi-colon, character is not a valid character for a FAT filesystem
label. This test used to succeed because prior to v4.2 of dosfstools
mkfs.vfat did not enforce the character restrictions for volume labels. So,
change the volume label string to be valid but contain symbol characters to
test odd volume labels.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>