ide: move read_sff_dma_status() method to 'struct ide_dma_ops'

Move apparently misplaced read_sff_dma_status() method from 'struct ide_tp_ops'
to 'struct ide_dma_ops', renaming it to dma_sff_read_status() and making only
required for SFF-8038i compatible IDE controller drivers (greatly cutting down
the number of initializers) as its only user (outside ide-dma-sff.c and such
drivers) appears to be ide_pci_check_simplex() which is only called for such
controllers...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>