scsi: docs: convert ncr53c8xx.txt to ReST

Link: https://lore.kernel.org/r/cover.1583136624.git.mchehab+huawei@kernel.org


Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>