MAINTAINERS: Update DW 8250 UART maintainership

Add myself as maintainer for DW 8250 UART and up it to Supported.

Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/be58b398-71ff-7c12-1bf1-a09181d9c80@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>