drm/gem: Add _locked postfix to functions that have unlocked counterpart

Add _locked postfix to drm_gem functions that have unlocked counterpart
functions to make GEM functions naming more consistent and intuitive in
regards to the locking requirements.

Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.d>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250322212608.40511-3-dmitry.osipenko@collabora.com