iio: adc: rockchip_saradc: remove unused variable in probe

The rate variable in the probe function of the saradc is a remnant
of a previous patch iteration. It is unused and thus produces a
compile time warning. Therefore remove it.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/rockchip_saradc.c

@@ -141,7 +141,6 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
 	struct resource	*mem;
 	int ret;
 	int irq;
-	u32 rate;
 
 	if (!np)
 		return -ENODEV;