crypto: arm64/poly1305 - ignore build files

Add arch/arm64/crypto/poly1305-core.S to .gitignore
as it's built from poly1305-core.S_shipped

Fixes: f569ca16 ("crypto: arm64/poly1305 - incorporate OpenSSL/CRYPTOGAMS NEON implementation")
Signed-off-by: NMatteo Croce <mcroce@redhat.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/.gitignore

 sha256-core.S
 sha512-core.S
+poly1305-core.S