power: regulator: max77686: Don't use switch() on bools

With gcc-5.3 we get a warning for using switch() on a bool type.
Rewrite these sections as if/else and update the one section that was
using 1/0 instead of true/false.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>

drivers/power/regulator/max77686.c

@@ -515,25 +515,19 @@ static int max77686_ldo_enable(struct udevice *dev, int op, bool *enable)
 
 		switch (on_off) {
 		case OPMODE_OFF:
-			*enable = 0;
+			*enable = false;
 			break;
 		case OPMODE_ON:
-			*enable = 1;
+			*enable = true;
 			break;
 		default:
 			return -EINVAL;
 		}
 	} else if (op == PMIC_OP_SET) {
-		switch (*enable) {
-		case 0:
-			on_off = OPMODE_OFF;
-			break;
-		case 1:
+		if (*enable)
 			on_off = OPMODE_ON;
-			break;
-		default:
-			return -EINVAL;
-		}
+		else
+			on_off = OPMODE_OFF;
 
 		ret = max77686_ldo_mode(dev, op, &on_off);
 		if (ret)
@@ -651,16 +645,10 @@ static int max77686_buck_enable(struct udevice *dev, int op, bool *enable)
 			return -EINVAL;
 		}
 	} else if (op == PMIC_OP_SET) {
-		switch (*enable) {
-		case 0:
-			on_off = OPMODE_OFF;
-			break;
-		case 1:
+		if (*enable)
 			on_off = OPMODE_ON;
-			break;
-		default:
-			return -EINVAL;
-		}
+		else
+			on_off = OPMODE_OFF;
 
 		ret = max77686_buck_mode(dev, op, &on_off);
 		if (ret)