media: admin-guide: add stm32-dma2d description

add stm32-dma2d description for dma2d driver
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>

Documentation/admin-guide/media/platform-cardlist.rst

@@ -60,6 +60,7 @@ s5p-mfc            Samsung S5P MFC Video Codec
 sh_veu             SuperH VEU mem2mem video processing
 sh_vou             SuperH VOU video output
 stm32-dcmi         STM32 Digital Camera Memory Interface (DCMI)
+stm32-dma2d        STM32 Chrom-Art Accelerator Unit
 sun4i-csi          Allwinner A10 CMOS Sensor Interface Support
 sun6i-csi          Allwinner V3s Camera Sensor Interface
 sun8i-di           Allwinner Deinterlace