drm/client: Switch drm_client_buffer_delete() to unlocked drm_gem_vunmap

drm/client: Switch drm_client_buffer_delete() to unlocked drm_gem_vunmap

The drm_client_buffer_delete() wasn't switched to unlocked GEM vunmapping
by accident when rest of drm_client code transitioned to the unlocked
variants of the vmapping functions. Make drm_client_buffer_delete() use
the unlocked variant. This fixes lockdep warning splat about missing
reservation lock when framebuffer is released.

Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/dri-devel/890f70db-68b0-8456-ca3c-c5496ef90517@collabora.com/T/
Fixes: 79e2cf2e7a19 ("drm/gem: Take reservation lock for vmap/vunmap operations")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221020213335.309092-1-dmitry.osipenko@collabora.com