[SCSI] mpt fusion: make mptsas_smp_handler update resid

This patch fixes mptsas_smp_handler to update both din_resid or
dout_resid on success. bsg can report back the residual.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>