[SCSI] libsas: correctly flush the LU queue on error recovery

The current sas_scsi_clear_queue_lu() is wrongly checking for commands
which match the pointer to the one passed in.  It should be checking for
commands which are on the same logical unit as the one passed in.  Fix
this by checking target pointer and LUN for equality.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>