serial: 8250_lpss: enable DMA on Intel Quark UART

DMA on Intel Quark SoC is a part of UART IP block. Enable it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>