dist/tools/cppcheck: Add missing hpp file name pattern

dist/tools/cppcheck/check.sh

@@ -17,7 +17,7 @@ else
 fi
 
 BRANCH=${1}
-FILEREGEX='\.([sScHh]|cpp)$'
+FILEREGEX='\.([CcHhSs]|[ch]pp)$'
 EXCLUDE='^(cpu/saml21/include/atmel/)|^(cpu/cortexm_common/include/)'
 
 # If no branch but an option is given, unset BRANCH.