crypto: testmgr - Use kmalloc memory for RSA input

As akcipher uses an SG interface, you must not use vmalloc memory
as input for it.  This patch fixes testmgr to copy the vmalloc
test vectors to kmalloc memory before running the test.

This patch also removes a superfluous sg_virt call in do_test_rsa.

Cc: <stable@vger.kernel.org>
Reported-by: Anatoly Pugachev <matorola@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>