Revert "crypto: testmgr - Disable rfc4543 test"

This reverts commit 9b9f9296a7b73fbafe0a0a6f2494eaadd97f9f73 as
all in-kernel implementations of GCM have been converted to the
new AEAD interface, meaning that they should now pass the updated
rfc4543 test.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>