pata-rb532-cf: use ata_sff_data_xfer32()

The biggest difference between rb532_pata_data_xfer() and
ata_sff_data_xfer32() is the call to ata_sff_pause() at the end of
rb532_pata_data_xfer() which I suppose to be unnecessary since it works
without. I've also tested using ata_sff_data_xfer() as replacement, but
since we know that the driver supports 32bit IO, using the optimised
version should be safe.

Signed-off-by: Phil Sutter <n0-1@freewrt.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>