winsys/radeon: fix bo with virtual address referencing mismatch

winsys/radeon: fix bo with virtual address referencing mismatch

If the same context try to flink and open the object, use the
same bo struct instead of opening a new gem handle for the object.
This way we avoid avoid having 2 different handle pointing to the
same kernel object which can latter lead to trouble with virtual
address.

Fix:
https://bugs.freedesktop.org/show_bug.cgi?id=60200

Signed-off-by: Martin Andersson <g02maran@gmail.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>