thermal: rockchip: use the usleep_range instead of udelay

Documentation/timers/timers-howto.txt recommends to use
usleep_range on delays > 10usec.
The usleep_range indeed reduces CPU load, since the udelay will busy wait
for enough loop cycles to achieve the desired delay.

Fixes commit b06c52db39fd ("thermal: rockchip:
handle the power sequence for tsadc controller").

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Suggested-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/rockchip_thermal.c

@@ -547,10 +547,10 @@ static void rk_tsadcv3_initialize(struct regmap *grf, void __iomem *regs,
 		regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_ON);
 		mdelay(10);
 		regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_OFF);
-		udelay(100); /* The spec note says at least 15 us */
+		usleep_range(15, 100); /* The spec note says at least 15 us */
 		regmap_write(grf, GRF_SARADC_TESTBIT, GRF_SARADC_TESTBIT_ON);
 		regmap_write(grf, GRF_TSADC_TESTBIT_H, GRF_TSADC_TESTBIT_H_ON);
-		udelay(200); /* The spec note says at least 90 us */
+		usleep_range(90, 200); /* The spec note says at least 90 us */
 	}
 
 	if (tshut_polarity == TSHUT_HIGH_ACTIVE)