radv: fix flushing indirect descriptors

Let say, we first bind a graphics pipeline that needs indirect
descriptors sets. The userdata pointers will be emitted at draw
time. Then if we bind a compute pipeline that doesn't need any
indirect descriptors, the driver will re-emit them for all
grpahics stages.

To avoid this to happen, just check the bind point type.

CC: 18.2 <mesa-stable@lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit 748f4cce)