crypto: x86/aes-ni-xts - rewrite and drop indirections via glue helper

The AES-NI driver implements XTS via the glue helper, which consumes
a struct with sets of function pointers which are invoked on chunks
of input data of the appropriate size, as annotated in the struct.

Let's get rid of this indirection, so that we can perform direct calls
to the assembler helpers. Instead, let's adopt the arm64 strategy, i.e.,
provide a helper which can consume inputs of any size, provided that the
penultimate, full block is passed via the last call if ciphertext stealing
needs to be applied.

This also allows us to enable the XTS mode for i386.

Tested-by: Eric Biggers <ebiggers@google.com> # x86_64
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>