virtio-crypto: call scheduler when we free unused buffs

For virtio-net we were getting CPU stall warnings, and fixed it by
calling the scheduler: see f8bb510 ("virtio_net: suppress cpu stall
when free_unused_bufs").

This driver is similar so theoretically the same logic applies.

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Message-Id: <20230609131817.712867-2-xianting.tian@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: Xianting Tian

drivers/crypto/virtio/virtio_crypto_core.c

@@ -480,6 +480,7 @@ static void virtcrypto_free_unused_reqs(struct virtio_crypto *vcrypto)
 			kfree(vc_req->req_data);
 			kfree(vc_req->sgs);
 		}
+		cond_resched();
 	}
 }