tape390_display: Direct --help output to stdout
tape390_display: Direct --help output to stdout

tape390_display writes output for --help to stderr. To be consistent
with other s390-tools and GNU coding guide lines, fix this by using
stdout for tool-generated usage help.

Reviewed-by: Jens Remus <9647a37a176c11c7fb6887065f43509d6f3a5d2d@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <e296756d5edaffcdbc7b9904859492ff25d3fce5@linux.ibm.com>
Signed-off-by: Jan Höppner <96138615ab4af0813785fa10d283f3d37eca3b78@linux.ibm.com>

ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools