media: stm32-dma2d: STM32 DMA2D driver

This V4L2 subdev m2m driver enables Chrom-Art Accelerator unit
of STMicroelectronics STM32 SoC series.

Currently support r2m, m2m, m2m_pfc functions.
- r2m, Filling a part or the whole of a destination image with a specific
  color.
- m2m, Copying a part or the whole of a source image into a part or the
  whole of a destination.
- m2m_pfc, Copying a part or the whole of a source image into a part or the
  whole of a destination image with a pixel format conversion.

[hverkuil: fix typo in commit log]

Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>