This patch adds uart support for MediaTek MT7620 and earlier SoCs.
The UART used by MT7620 is incompatible with the ns16550a driver.
All registers of this UART have different addresses. A special 16-bit
register for Divisor Latch is used to set the baudrate instead of the
original two 8-bit registers (DLL and DLM).
The driver supports of-platdata which is useful for tiny SPL.
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
