drm/gem: Change locked/unlocked postfix of drm_gem_v/unmap() function names

Make drm/gem API function names consistent by having locked function
use the _locked postfix in the name, while the unlocked variants don't
use the _unlocked postfix. Rename drm_gem_v/unmap() function names to
make them consistent with the rest of the API functions.

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/20250322212608.40511-2-dmitry.osipenko@collabora.com