mfd: ioc3: Add driver for SGI IOC3 chip

mfd: ioc3: Add driver for SGI IOC3 chip

SGI IOC3 chip has integrated ethernet, keyboard and mouse interface.
It also supports connecting a SuperIO chip for serial and parallel
interfaces. IOC3 is used inside various SGI systemboards and add-on
cards with different equipped external interfaces.

Support for ethernet and serial interfaces were implemented inside
the network driver. This patchset moves out the not network related
parts to a new MFD driver, which takes care of card detection,
setup of platform devices and interrupt distribution for the subdevices.

Serial portion: Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Network part: Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Network part: Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-serial@vger.kernel.org