iio:accel:mma8452: coding style cleanup

Some coding style cleanups, mainly indicated by checkpatch.pl, which
includes indentation changes, drop spaces after casts and befor tabs.
Also insert empty lines after logical blocks and before unconditional
returns.

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>