iio:accel:bmc150-accel: code style cleanup

Apply the following coding style changes as indicated by checkpatch.pl in
strict mode:
  - Please don't use multiple blank lines
  - braces {} should be used on all arms of this statement (if/else)
  - Alignment should match open parenthesis
  - Please don't use multiple blank lines
  - Blank lines aren't necessary after an open brace '{'
  - Missing a blank line after declarations
  - No space is necessary after a cast

Also wrap/consolidate error messages to fit 80 characters per line and
rework a comment.

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Reviewed-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>