scsi: pm80xx: Add controller SCSI host fatal error uevents

scsi: pm80xx: Add controller SCSI host fatal error uevents

Add pm80xx_fatal_error_uevent_emit() which is called when the pm80xx
driver encouters a fatal error. The uevent has the following additional
custom key/value pair sets:

 - DRIVER: driver name, pm80xx in this case
 - HBA_NUM: the scsi host id of the device
 - EVENT_TYPE: to indicate a fatal error
 - REPORTED_BY: either driver or firmware

The uevent is anchored to the kernel object that represents the SCSI
controller, which includes other useful core variables, such as, ACTION,
DEVPATH, SUBSYSTEM, and more.

The fatal_error_uevent_emit() function is called when the controller
fatal error state changes. Since this doesn't happen often for a
specific SCSI host, there is no worries of a uevent storm.

Signed-off-by: Salomon Dushimirimana <salomondush@google.com>
Link: https://lore.kernel.org/r/20250616190018.2136260-1-salomondush@google.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>