pinctrl/abx500: beautify the ABX500 pin control driver

This patch provides some superficial changes to the driver to
aid with readability and maintainability. We're mostly fixing
things like white-space errors, spreading out code which as
been clumped together impeding readability and comment layout,
such as using the new "/**" comment start for function headers
etc. No code semantics were harmed in the making of this patch.
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>