hwmon: (pmbus) Don't unnecessarily crash the kernel

pmbus code currently crashes the kernel if it detects an internal
implementation error. While the detected condition suggests that there
is a bug in the code, it is hardly fatal. Therefore, it should not
trigger a crash. Replace BUG() with WARN().
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pmbus/pmbus_core.c

@@ -686,7 +686,7 @@ static int pmbus_get_boolean(struct pmbus_data *data, struct pmbus_boolean *b,
 	if (!s1 && !s2) {
 		ret = !!regval;
 	} else if (!s1 || !s2) {
-		BUG();
+		WARN(1, "Bad boolean descriptor %p: s1=%p, s2=%p\n", b, s1, s2);
 		return 0;
 	} else {
 		long v1, v2;