regulator: maintainers: Update email address for Liam

Liam sent a patch[1] to update his email, but it only updates the
maintainer entry for ASoC. This patch updates the entry for regulator subsystem
to ensure get_maintainer.pl returns correct email address for maintainers.

[1] https://lkml.org/lkml/2013/1/15/344



Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>