acpi: arm64 doesn't support ACPI 1.0 RSDP, report when we see one

arm64 requires ACPI RSDP Revision 2.0 since it requires 64-bit physical
addresses. It is an error worth reporting if we have a RSDP pointer, but
it points to the wrong version.

Sponsored by: Netflix
Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D36404