scsi: NCR5380: Check for bus reset

[ Upstream commit 6b0e87a6aafe12d75c2bea6fc8e49e88b98b3083 ]

The SR_RST bit isn't latched. Hence, detecting a bus reset isn't reliable.
When it is detected, the right thing to do is to drop all connected and
disconnected commands. The code for that is already present so refactor it and
call it when SR_RST is set.

Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>