drm/msm: Do not unpin/evict exported dma-buf's

Our initial logic for excluding dma-bufs was not quite right.  In
particular we want msm_gem_get/put_pages() path used for exported
dma-bufs to increment/decrement the pin-count.

Also, in case the importer is vmap'ing the dma-buf, we need to be
sure to update the object's status, because it is now no longer
potentially evictable.

Fixes: 63f17ef8

 drm/msm: Support evicting GEM objects to swap
Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20210426235326.1230125-1-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>