clover: use pipe_resource references
v2: buffers are created with one reference. v3: add pipe_resource reference to mapping object v4: rename to pres and drop inline initializers CC: "17.0 13.0" <mesa-stable@lists.freedesktop.org> Signed-off-by:Jan Vesely <jan.vesely@rutgers.edu> Reviewed-by:
Francisco Jerez <currojerez@riseup.net>