We want to remove per minor debugfs directories. Start by stopping
drivers from adding anything inside of those in the mid layer callback.

v2: drop it for the accel node as well
Signed-off-by: Christian König <christian.koenig@amd.com>
Tested-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230829110115.3442-2-christian.koenig@amd.com