crypto: arm64/poly1305 - incorporate OpenSSL/CRYPTOGAMS NEON implementation

This is a straight import of the OpenSSL/CRYPTOGAMS Poly1305 implementation
for NEON authored by Andy Polyakov, and contributed by him to the OpenSSL
project. The file 'poly1305-armv8.pl' is taken straight from this upstream
GitHub repository [0] at commit ec55a08dc0244ce570c4fc7cade330c60798952f,
and already contains all the changes required to build it as part of a
Linux kernel module.

[0] https://github.com/dot-asm/cryptogams

Co-developed-by: Andy Polyakov <appro@cryptogams.org>
Signed-off-by: Andy Polyakov <appro@cryptogams.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>