s390/tape: Remove 34xx Read Opposite error recovery

s390/tape: Remove 34xx Read Opposite error recovery

On old native type 3490 tape devices a Read Opposite error recovery
procedure on Error Recovery Action Code (ERA) 26 was issued if a Read
Forward command failed. This recovery procedure was implemented with the
Read Backward command.

As a preparation for a subsequent commit, that adds support for bigger
block sizes, remove the 34xx ERA 26 related recovery code. The recovery
code would need to be adapted to the bigger block sizes, without any
possibility to be tested, as modern Virtual Tape Servers (VTS) do
neither report ERA 26 on a Read Forward command failure nor support the
error recovery procedure anymore.

Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>