added access chef for /dev/i2c-x

git-svn-id: svn://svn.code.sf.net/p/fhem/code@5393 2b470e98-0d58-463d-a4d8-8e2adae1ed80
OWX_ASYNC: add async OWX (works with FRM so far)

git-svn-id: svn://svn.code.sf.net/p/fhem/code@5394 2b470e98-0d58-463d-a4d8-8e2adae1ed80