crypto: qat - Fix a double free in adf_create_ring

In adf_create_ring, if the callee adf_init_ring() failed, the callee will
free the ring->base_addr by dma_free_coherent() and return -EFAULT. Then
adf_create_ring will goto err and the ring->base_addr will be freed again
in adf_cleanup_ring().

My patch sets ring->base_addr to NULL after the first freed to avoid the
double free.

Fixes: a672a9dc ("crypto: qat - Intel(R) QAT transport code")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>