MIPS: IP22/IP28: Improve GIO support

- added interrupt support for GIO devices
- improved detection of GIO cards on Indigo2
- added more known GIO cards

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7055/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>