[ARDUINOMEGA] Fix comment position

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7091 35acf78f-673a-0410-8e92-d51de3d6d3f4
[AVR] Use osal provided OSAL_ST_FREQUENCY instead of redefining it

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7092 35acf78f-673a-0410-8e92-d51de3d6d3f4