ata: libata: Remove ata_noop_qc_prep()

ata: libata: Remove ata_noop_qc_prep()

The function ata_noop_qc_prep(), as its name implies, does nothing and
simply returns AC_ERR_OK. For drivers that do not need any special
preparations of queued commands, we can avoid having to define struct
ata_port qc_prep operation by simply testing if that operation is
defined or not in ata_qc_issue(). Make this change and remove
ata_noop_qc_prep().

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>