mfd: ti_am335x_tscadc: Simplify divisor calculation

Let's rewrite this on a single line, it does not hurt the readability
and saves a useless temporary variable.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211015081506.933180-16-miquel.raynal@bootlin.com

drivers/mfd/ti_am335x_tscadc.c

@@ -122,7 +122,6 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 	const __be32 *cur;
 	u32 val;
 	int err, ctrl;
-	int clock_rate;
 	int tsc_wires = 0, adc_channels = 0, total_channels;
 	int readouts = 0;
 
@@ -212,11 +211,8 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 		err = PTR_ERR(clk);
 		goto err_disable_clk;
 	}
-	clock_rate = clk_get_rate(clk);
-	tscadc->clk_div = clock_rate / ADC_CLK;
 
-	/* TSCADC_CLKDIV needs to be configured to the value minus 1 */
-	tscadc->clk_div--;
+	tscadc->clk_div = (clk_get_rate(clk) / ADC_CLK) - 1;
 	regmap_write(tscadc->regmap, REG_CLKDIV, tscadc->clk_div);
 
 	/* Set the control register bits */