Specify checkstyle suppression in config file.

Backported from OVX
 https://review.gerrithub.io/3549
-- description by Marc --
  The idea is to have maven and eclipse share the same checkstyle config.
  We still setup the suppression, but inside the sun_checks.xml file.
  Here we’re using a variable that is standard in Eclipse, but unknown by Maven.
  The propertiesLocation allows us to define the variable in the scope of Maven.

  See here for more info: http://rolf-engelhard.de/2011/04/using-the-same-suppression-filter-for-checkstyle-in-eclipse-and-maven/
----

Change-Id: I4d1083002db94556d31febdca9fc6d19745a0ce8
diff --git a/pom.xml b/pom.xml
index a4939ee..2438940 100644
--- a/pom.xml
+++ b/pom.xml
@@ -56,9 +56,7 @@
         <version>${checkstyle-plugin.version}</version>
         <configuration>
           <configLocation>conf/checkstyle/sun_checks.xml</configLocation>
-          <suppressionsLocation>
-            ${basedir}/conf/checkstyle/onos_suppressions.xml
-          </suppressionsLocation>
+          <propertiesLocation>${basedir}/conf/checkstyle/checkstyle_maven.properties</propertiesLocation>
           <failsOnError>false</failsOnError>
           <logViolationsToConsole>true</logViolationsToConsole>
         </configuration>
@@ -418,9 +416,7 @@
             - maven-pmd-plugin configuration in pom.xml
               (under build and reporting)
           -->
-          <suppressionsLocation>
-             ${basedir}/conf/checkstyle/onos_suppressions.xml
-          </suppressionsLocation>
+          <propertiesLocation>${basedir}/conf/checkstyle/checkstyle_maven.properties</propertiesLocation>
         </configuration>
         <reportSets>
           <reportSet>