Fix negative int pattern

Author: gmarcosb

src/app/zap-templates/zcl/zcl.xsd

@@ -10,7 +10,7 @@ This schema describes the format of the XML files, that describe the ZCL specifi
   </xs:annotation>
   <xs:simpleType name="integerWithHex">
     <xs:restriction base="xs:string">
-      <xs:pattern value="[-+]?0x[0-9A-Fa-f]+|[0-9]+"/>
+      <xs:pattern value="[-+]?(0x[0-9A-Fa-f]+|[0-9]+)"/>
     </xs:restriction>
   </xs:simpleType>
   <xs:complexType name="access">