drm: add meson drm debugfs node [1/1]

drm: add meson drm debugfs node [1/1]

PD#SWPL-12289

Problem:
drm driver has no debug sysfs file

Solution:
add follow sysfs node
1. dump the osd register
/sys/kernel/debug/dri/%minor%/vpu/reg_dump
2. dump the gem buffer image
/sys/kernel/debug/dri/%minor%/vpu/dump
3. set the gem buffer image store path
/sys/kernel/debug/dri/%minor%/vpu/imgpath
4. set 1 to disable the osd plane
/sys/kernel/debug/dri/%minor%/vpu/blank

Verify:
g12a-u200

Change-Id: I10746d65b09d3b530dc22720b8cee669fa120dde
Signed-off-by: Ao Xu <ao.xu@amlogic.com>