crypto: testmgr - add another gcm(aes) testcase

Add an additional gcm(aes) test case that triggers the code path in
the new arm64 driver that deals with tail blocks whose size is not
a multiple of the block size, and where the size of the preceding
input is a multiple of 64 bytes.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>