Increase maximum configurable Ember power to 20dBm

Signed-off-by: Chris Jackson <chris@cd-jackson.com>

Author: cdjackson

org.openhab.binding.zigbee.ember/src/main/resources/OH-INF/thing/controller_ember.xml

@@ -78,11 +78,12 @@
 				</options>
 			</parameter>
 
-			<parameter name="zigbee_txpower" type="integer" min="0" max="8" groupName="ember">
+			<parameter name="zigbee_txpower" type="integer" min="0" max="20" groupName="ember">
 				<label>Transmit Power</label>
 				<description>Sets the Ember transmit power</description>
 				<default>0</default>
 				<options>
+					<option value="20">Maximum</option>
 					<option value="8">High</option>
 					<option value="0">Normal</option>
 				</options>