Add checkstyle check to graphics package

Test: None
Change-Id: I1c8342dda2678917e245e48ab141b2953a522197

PREUPLOAD.cfg

 [Hook Scripts]
 checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
                   -fw core/java/android/
+                      graphics/java/android
                       core/tests/coretests/src/android/
                       packages/PrintRecommendationService/
                       packages/PrintSpooler/