MAINTAINERS: Update Synopsys DesignWare I2C to Supported

The actual status of the code is Supported (from x86 perspective).

Reported-by:  <dave.hansen@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
[wsa: fixed "DesignWare" spelling]
Signed-off-by: Wolfram Sang <wsa@kernel.org>