clk: sunxi-ng: sun55i-a523-r-ccu: Mark bus-r-dma as critical

clk: sunxi-ng: sun55i-a523-r-ccu: Mark bus-r-dma as critical

The "bus-r-dma" clock in the A523's PRCM clock controller is also
referred to as "DMA_CLKEN_SW" or "DMA ADB400 gating". It is unclear how
this ties into the DMA controller MBUS clock gate; however if the clock
is not enabled, the DMA controller in the MCU block will fail to access
DRAM, even failing to retrieve the DMA descriptors.

Mark this clock as critical. This sort of mirrors what is done for the
main DMA controller's MBUS clock, which has a separate toggle that is
currently left out of the main clock controller driver.

Fixes: 8cea339cfb81 ("clk: sunxi-ng: add support for the A523/T527 PRCM CCU")
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patch.msgid.link/20251020171059.2786070-6-wens@kernel.org
Signed-off-by: Chen-Yu Tsai <wens@kernel.org>