drm/ttm: fix locking in vmap/vunmap TTM GEM helpers

drm/ttm: fix locking in vmap/vunmap TTM GEM helpers

commit dbd0da2453c694f2f74651834d90fb280b57f151 upstream.

I've stumbled over this while reviewing patches for DMA-buf and it looks
like we completely messed the locking up here.

In general most TTM function should only be called while holding the
appropriate BO resv lock. Without this we could break the internal
buffer object state here.

Only compile tested!

Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: 43676605f890 ("drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers")
Cc: stable@vger.kernel.org
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220715111533.467012-1-christian.koenig@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>