iio: accel: mma7660: Warn about failure to put device in stand-by in .remove()

Whan an i2c driver's remove function returns a non-zero error code
nothing happens apart from emitting a generic error message. Make this
error message more device specific and return zero instead.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211025195007.84541-1-u.kleine-koenig@pengutronix.de


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>