st/xa: Fix a memory leak
Free the context after destruction. Cc: mesa-stable@lists.freedesktop.org Signed-off-by:Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by:
Sinclair Yeh <syeh@vmware.com> Reviewed-by:
Emil Velikov <emil.velikov@collabora.com> (cherry picked from commit 7fce3ca3)