trm290: do hook dma_host_{on,off} methods (take 2)

Using default methods caused the chip's DMA PRD count registers, inadvertently
starting DMA!  While fixing it, also do:

- get rid of the 'ide_' prefixes in several functions for which the prefix in
  the method's name has been 'ide_' ectomized already;

- align the code hooking the IDE DMA methods in init_hwif_trm290()...

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