regulator: Fetch enable gpiods nonexclusive

Since the core regulator code is treating GPIO descriptors as
nonexclusive, i.e. it assumes that the enable GPIO line may be
shared with several regulators, let's add the flag introduced
for fixing this problem on fixed regulators to all drivers
fetching GPIO descriptors to avoid possible regressions.

Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>