regulator: lp87565: Use bitfield helpers

Use the FIELD_PREP() helper, instead open-coding the same operation.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://msgid.link/r/5e878[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/lp87565-regulator.c

···
  * Copyright (C) 2017 Texas Instruments Incorporated - https://www.ti.com/
  */
 
+#include <linux/bitfield.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
···
 
 	ret = regmap_update_bits(rdev->regmap, regulators[id].ctrl2_reg,
 				 LP87565_BUCK_CTRL_2_SLEW_RATE,
-				 reg << __ffs(LP87565_BUCK_CTRL_2_SLEW_RATE));
+				 FIELD_PREP(LP87565_BUCK_CTRL_2_SLEW_RATE, reg));
 	if (ret) {
 		dev_err(&rdev->dev, "SLEW RATE write failed: %d\n", ret);
 		return ret;