[SCSI] fas216: Use scsi_eh API for REQUEST_SENSE invocation

Use new scsi_eh_prep/restor_cmnd() for synchronous REQUEST_SENSE
invocation.  This also converts the driver to the new accessor based
scatterlist implementation.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>