[PATCH] libata: clean up variable name usage in xlat related functions

Variable names in xlat functions are quite confusing now.  'scsicmd'
is used for CDB while qc->scsicmd points to struct scsi_cmnd while
'cmd' is used for struct scsi_cmnd.

This patch cleans up variable names in xlat functions such that 'scmd'
is used for struct scsi_cmnd and 'cdb' for CDB.  Also, 'scmd' local
variable is added if qc->scsicmd is used multiple times.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>