ide: remove chipset field from hw_regs_t

* Convert host drivers that still use hw_regs_t's chipset field to use
  the one in struct ide_port_info instead.

* Move special handling of ide_pci chipset type from ide_hw_configure()
  to ide_init_port().

* Remove chipset field from hw_regs_t.

While at it:
- remove stale comment in delkin_cb.c

There should be no functional changes caused by this patch.

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