[S390] tape: Compression overwrites crypto setting

After switching compression on/off with the mt command, tape encryption is no
longer working. The reason for that is, that the modeset_byte is set to
the compression value instead of using bitwise and/or bit operations to
enable/disable the corresponding bit.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>