rockchip: udev: grant video group access to MPP codec devices and DMA-heaps (#10085)

The current Rockchip BSP exposes its hardware video codec stack (VEPU/VDPU
via the MPP framework) through /dev/mpp_service, and the MPP userspace
(rkmpp / ffmpeg-rockchip, Jellyfin, ...) allocates all of its frame and
stream buffers from the kernel DMA-heaps under /dev/dma_heap/*.

60-media.rules already covers media* and rga, but neither mpp_service nor
the dma_heap nodes, so hardware encode/decode only works as root: both are
root-only by default. Granting just mpp_service is not enough on its own --
the encoder still fails at init ("MppBufferService get_group failed ...
type 1") because rkmpp cannot open /dev/dma_heap/system (root root 0600)
to allocate its buffers.

Add rules for both, mirroring the existing media/rga entries
(GROUP="video", MODE="0660"), so members of the video group can use
hardware video encode/decode without elevated privileges. dma_heap is
matched by subsystem because the heap node's kernel name is just "system".

Verified on a ROCK 5B (RK3588): with both rules a non-root video-group
user runs h264_rkmpp / hevc_rkmpp encode/transcode successfully, where
before it failed at MPP init.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: yisding

packages/bsp/rockchip/60-media.rules

@@ -1,2 +1,4 @@
 KERNEL=="media*", MODE="0660", GROUP="video"
 KERNEL=="rga", MODE="0660", GROUP="video"
+KERNEL=="mpp_service", MODE="0660", GROUP="video"
+SUBSYSTEM=="dma_heap", MODE="0660", GROUP="video"