scsi: ufs: core: Make fault injection dynamically configurable per HBA

scsi: ufs: core: Make fault injection dynamically configurable per HBA

The UFS driver has two driver-specific fault injection mechanisms
(trigger_eh and timeout). Each fault injection configuration can only be
specified by a module parameter and cannot be reconfigured without
reloading the driver. Also, each configuration is common to all HBAs.

This change adds the following subdirectories for each UFS HBA when
debugfs is enabled:

  /sys/kernel/debug/ufshcd/<HBA>/timeout_inject
  /sys/kernel/debug/ufshcd/<HBA>/trigger_eh_inject

Each fault injection attribute can be dynamically set per HBA by a
corresponding file in these directories.

This is tested with QEMU UFS devices.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/20231118124443.1007116-1-akinobu.mita@gmail.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>