serial: 8250_dw: Update the list of OF headers used by driver

The of_irq.h and of_platform.h are not used by the driver. On the
other hand, the mod_devicetable.h missed. Drop the former two and
add the latter one.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220509161911.37164-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>