x86/crypto: Enable objtool in crypto code

Now that all the stack alignment prologues have been cleaned up in the
crypto code, enable objtool.  Among other benefits, this will allow ORC
unwinding to work.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/fc2a1918c50e33e46ef0e9a5de02743f2f6e3639.1614182415.git.jpoimboe@redhat.com