[SCSI] mptspi: Fix for incorrect data underrun errata

Errata:
Certain conditions on the scsi bus may casue the 53C1030 to incorrectly signal
a SCSI_DATA_UNDERRUN to the host.

Workaround 1:
For an Errata on LSI53C1030 When the length of request data
and transfer data are different with result of command (READ or VERIFY),
DID_SOFT_ERROR is set.

Workaround 2:
For potential trouble on LSI53C1030. It is checked whether the length of
request data is equal to the length of transfer and residual.
MEDIUM_ERROR is set by incorrect data.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>