internal/cpu: remove unused arm64 capabilities
internal/cpu: remove unused arm64 capabilities

Change-Id: I038b0fe165931b8ec3ef59f08dc73c8128d56572
Reviewed-on: https://go-review.googlesource.com/c/go/+/261365
Trust: Martin Möhrmann <9c82b83f348009b39856043bb9ed3ef41e171aeb@google.com>
Run-TryBot: Martin Möhrmann <9c82b83f348009b39856043bb9ed3ef41e171aeb@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

golang/go,nawawi/go,CAFxX/go,nawawi/go,golang/go,golang/go,CAFxX/go,cloudflare/go,CAFxX/go,golang/go,cloudflare/go,cloudflare/go,golang/go,nawawi/go,CAFxX/go,golang/go,CAFxX/go,CAFxX/go,cloudflare/go,cloudflare/go,cloudflare/go,nawawi/go,cloudflare/go,golang/go,CAFxX/go,golang/go,nawawi/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,nawawi/go