scsi: pm80xx: Add sysfs attribute to check controller hmi error

A new sysfs variable 'ctl_hmi_error' is being introduced to give the error
details if the MPI initialization fails

Using the 'ctl_hmi_error' sysfs variable we can check the error details:

    linux-2dq0:~# cat /sys/class/scsi_host/host*/ctl_hmi_error
    0x00000000
    0x00000000
    0x00000000

Link: https://lore.kernel.org/r/20210415103352.3580-3-Viswas.G@microchip.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: Martin K. Petersen <martin.petersen@oracle.com>