MAINTAINERS: Add missed files related to Synopsys DesignWare UART

MAINTAINERS: Add missed files related to Synopsys DesignWare UART

8250_dw has been split to library part and the driver, the library
is being used by 8250_lpss, which represents Synosys DesignWare UART
(with optional Synopsys Designware DMA) enumerated by PCI.

Add missed above mentioned files to the database record for review.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200305123108.41320-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>