scsi: scsi_debug: Define grammar to remove added error injection

The grammar to remove error injection is a line with fixed 3 columns
separated by spaces.

First column is fixed to "-". It tells this is a removal operation.  Second
column is the error code to match.  Third column is the scsi command to
match.

For example the following command would remove timeout injection of inquiry
command:

    echo "- 0 0x12" > /sys/kernel/debug/scsi_debug/0:0:0:1/error

Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
Link: https://lore.kernel.org/r/20231010092051.608007-4-haowenchao2@huawei.com


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>