The purpose of the vdd_handler does not make sense. We remove it
and use a generic approach instead. A new ios_handler is added, the
purpose of which e.g. can be to control GPIO pins to a levelshifter.

Previously the vdd_handler was also used for making additional
changes to the power register bits. This option is superfluous and is
therefore removed.

Adaptaptions from the old vdd_handler to the new ios_handler is done for
mach-ux500 board, which was the only one using the vdd_handler.

This patch is based upon a patch from Sebastian Rasmussen.
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Rasmussen <sebastian.rasmussen@stericsson.com>
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>