staging: iio: accel: Removed unnecessary else expression.

This patch fixes "else is not generally useful after a break or return"
checkpatch.pl warning in adis16220_core.c

Signed-off-by: Gulsah Kose <gulsah.1004@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>