ARM: mach-shmobile: add 3.3V and 1.8V fixed regulators to mackerel

Drivers for several devices on mackerel, including all SDHI instances, the
MMCIF controller and the SMSC9220 ethernet chip use regulators to control
power supply to their devices. MMC drivers need to be able to at least
retrieve voltage values from supplying regulators, whereas the smsc911x
driver only enables and disables chip power supplies without further looking
at them. This patch adds two fixed voltage regulators to describe 1.8V and
3.3V supplies on the board and a dummy regulator for SMSC9220.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>