PORT_MFD is not in use since commit1bd187de53("x86, intel-mid: remove Intel MID specific serial support") Remove leftover. Fixes:1bd187de53("x86, intel-mid: remove Intel MID specific serial support") Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>