scsi: pm80xx: Add sysfs attribute to check MPI state

A new sysfs variable 'ctl_mpi_state' is being introduced to check the state
of MPI.

Using the 'ctl_mpi_state' sysfs variable we can check the MPI state:

    linux-2dq0:~# cat /sys/class/scsi_host/host*/ctl_mpi_state
    MPI is successfully initialized

Link: https://lore.kernel.org/r/20210415103352.3580-2-Viswas.G@microchip.com


Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vishakha Channapattan <vishakhavc@google.com>
Signed-off-by: Viswas G <Viswas.G@microchip.com>
Signed-off-by: Ruksar Devadi <Ruksar.devadi@microchip.com>
Signed-off-by: Ashokkumar N <Ashokkumar.N@microchip.com>
Signed-off-by: Radha Ramachandran <radha@google.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>