power: supply: cpcap-charger: Simplify bool conversion

Fix the following coccicheck warning:
./drivers/power/supply/cpcap-charger.c:416:31-36: WARNING: conversion to
bool not needed here
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/cpcap-charger.c

@@ -465,7 +465,7 @@ static bool cpcap_charger_vbus_valid(struct cpcap_charger_ddata *ddata)
 
 	error = iio_read_channel_processed(channel, &value);
 	if (error >= 0)
-		return value > 3900 ? true : false;
+		return value > 3900;
 
 	dev_err(ddata->dev, "error reading VBUS: %i\n", error);