drm/locking: fix __stack_depot_* name conflict

Commit cd06ab2f ("drm/locking: add backtrace for locking contended
locks without backoff") added functions named __stack_depot_* in drm
which conflict with stack depot. Rename to __drm_stack_depot_*.

v2 by Jani:
- Also rename __stack_depot_print

References: https://lore.kernel.org/r/20211015202648.258445ef@canb.auug.org.au


Fixes: cd06ab2f ("drm/locking: add backtrace for locking contended locks without backoff")
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018085113.27033-1-jani.nikula@intel.com
(cherry picked from commit c4f08d72)