In the past, the data for mb-skcipher test has been allocated
twice, that means the first allcated memory area is without
free, which may cause a potential memory leakage. So this
patch is to remove one allocation to fix this error.

Fixes: e161c593 ("crypto: tcrypt - add multibuf skcipher...")
Signed-off-by: Zhang Yiqun <zhangyiqun@phytium.com.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>