crypto: x86/nhpoly1305 - eliminate unnecessary CFI wrappers

Since the CFI implementation now supports indirect calls to assembly
functions, take advantage of that rather than use wrapper functions.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>