ARM: s3c64xx: Tidy up handling of regulator GPIO lookups

Rather than unconditionally registering the GPIO lookup table only do so
for devices that require it.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
[Fixed up to also handle wm5102 and wm5102 reva]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>