drm/bridge: synopsys: Add DW DPTX Controller support library

drm/bridge: synopsys: Add DW DPTX Controller support library

The DW DP TX Controller is compliant with the DisplayPort Specification
Version 1.4 with the following features:

* DisplayPort 1.4a
* Main Link: 1/2/4 lanes
* Main Link Support 1.62Gbps, 2.7Gbps, 5.4Gbps and 8.1Gbps
* AUX channel 1Mbps
* Single Stream Transport(SST)
* Multistream Transport (MST)
* Type-C support (alternate mode)
* HDCP 2.2, HDCP 1.3
* Supports up to 8/10 bits per color component
* Supports RBG, YCbCr4:4:4, YCbCr4:2:2, YCbCr4:2:0
* Pixel clock up to 594MHz
* I2S, SPDIF audio interface

Add library with common helpers to make it can be shared with
other SoC.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20250822063959.692098-3-andyshrk@163.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>