Synchronize with 2.5.25.

Incorporate IDE-94, as well as 95, 96, 97 and 98-pre as announced by Bartek and
unfortunately still not included in 2.5.25, which makes admittedly things
still fall appart:

Missing changelog for 98-pre by Bartlomiej Zolnierkiewicz (BTW.  Handling
Unicode should be essential at least to make proper crediting of many many
peoples possible!) follows here:

 - add missing channel->lock unlocking/locking and fix some comments
   in ide_timer_expiry()

 - allow PCI drivers to disable autodma in ->init_dma()
   (bug introduced in IDE 97, affects sl82c105.c only)

   noticed by Russell King

 - alim15x3.c, if revision is <= 0x20 disable autodma

 - remove unneeded checks (drive.dn > 3) from pdc202xx.c and sis5513.c

 - use block layer wrappers

And my additions follow:

 - Fix TCQ code. Patch based on work by Alexander Atanasov.

 - Use the FreeBSD derived request handler return values:

	ATA_OP_FINISHED
	ATA_OP_CONTINUES
	ATA_OP_RELEASED
	ATA_OP_READY	/* for status ready reporting during poll */

 - PMAC compilation fix by Paul Mackerras.

 - Simplify the ata_status_poll function significantly.

 - Fix logic used to prevent drive IRQ assertion from drive on channels sharing
   our interrupt.

NOTE: We will move it later to the time where a request is really finished
soon.

 - Don't use ata_busy_poll() use ata_status_poll() instead. This increases code
   unification.

NOTE: We should maybe invent some way to prevent the error recovery path to be
taken at all. In esp to prevent ata_error from trying to reissue commands.