dt-bindings: hwmon: (ntc_thermistor) add B57891S0103 thermistor from Epcos

These are Negative Temperature Coefficient thermistors, like the others
in the list.
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt

@@ -4,6 +4,7 @@ NTC Thermistor hwmon sensors
 Requires node properties:
 - "compatible" value : one of
 	"epcos,b57330v2103"
+	"epcos,b57891s0103"
 	"murata,ncp15wb473"
 	"murata,ncp18wb473"
 	"murata,ncp21wb473"