pdc202xx_new: remove ->init_setup

* Split off pdc20270_get_dev2() helper from init_setup_pdc20270().

* Merge init_setup_{pdcnew,pdc20270,pdc20276}() into pdc202new_init_one().

While at it:

* Change KERN_ level of interrupt fixup message from KERN_WARNING to KERN_INFO.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>