ARM: pxa: Use REGULATOR_SUPPLY macro

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Tested-by: Paul Parsons <lost.distance@yahoo.com>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>