iio: imu: kmx61: kmx61_set_wake_up_odr() can be static

drivers/iio/imu/kmx61.c:422:5: sparse: symbol 'kmx61_set_wake_up_odr' was not declared. Should it be static?

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>