crypto: fix a memory leak in rsa-kcs1pad's encryption mode

The encryption mode of pkcs1pad never uses out_sg and out_buf, so
there's no need to allocate the buffer, which presently is not even
being freed.

CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: linux-crypto@vger.kernel.org
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Dan Aloni <dan@kernelim.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>