iio: adc: mxs-lradc: Disable the clock on probe failure

We should disable lradc->clk in the case of errors in the probe function.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: <Stable@vger.kernel.org>