iio: srf08: add device tree binding for srf02 and srf10

add trivial device tree binding "devantech,srf02" and "devantech,srf10"

Signed-off-by: Andreas Klinger <ak@it-klinger.de>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/trivial-devices.txt

@@ -46,7 +46,9 @@ dallas,ds1775		Tiny Digital Thermometer and Thermostat
 dallas,ds3232		Extremely Accurate I²C RTC with Integrated Crystal and SRAM
 dallas,ds4510		CPU Supervisor with Nonvolatile Memory and Programmable I/O
 dallas,ds75		Digital Thermometer and Thermostat
+devantech,srf02		Devantech SRF02 ultrasonic ranger in I2C mode
 devantech,srf08		Devantech SRF08 ultrasonic ranger
+devantech,srf10		Devantech SRF10 ultrasonic ranger
 dlg,da9053		DA9053: flexible system level PMIC with multicore support
 dlg,da9063		DA9063: system PMIC for quad-core application processors
 domintech,dmard09	DMARD09: 3-axis Accelerometer