Move qmp_query_sgx_capabilities() from target/i386/monitor.c to
hw/i386/sgx.c, removing the sgx_get_capabilities() indirection.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211007175612.496366-4-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>