regulator: fixed: Convert to use GPIO descriptor only

As we augmented the regulator core to accept a GPIO descriptor instead
of a GPIO number, we can augment the fixed GPIO regulator to look up
and pass that descriptor directly from device tree or board GPIO
descriptor look up tables.

Some boards just auto-enumerate their fixed regulator platform devices
and I have assumed they get names like "fixed-regulator.0" but it's
pretty hard to guess this. I need some testing from board maintainers to
be sure. Other boards are straight forward, using just plain
"fixed-regulator" (ID -1) or "fixed-regulator.1" hammering down the
device ID.

It seems the da9055 and da9211 has never got around to actually passing
any enable gpio into its platform data (not the in-tree code anyway) so we
can just decide to simply pass a descriptor instead.

The fixed GPIO-controlled regulator in mach-pxa/ezx.c was confusingly named
"*_dummy_supply_device" while it is a very real device backed by a GPIO
line. There is nothing dummy about it at all, so I renamed it with the
infix *_regulator_* as part of this patch set.

Intel MID portions tested by Andy.

Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> # Check the x86 BCM stuff
Acked-by: Tony Lindgren <tony@atomide.com> # OMAP1,2,3 maintainer
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>