Revert "hw/i386: pass RNG seed via setup_data entry"

Revert "hw/i386: pass RNG seed via setup_data entry"

This reverts commit 67f7e426e53833a5db75b0d813e8d537b8a75bd2.

Additionally to the automatic revert, I went over the code
and dropped all mentions of legacy_no_rng_seed manually,
effectively reverting a combination of 2 additional commits:

    commit ffe2d2382e5f1aae1abc4081af407905ef380311
    Author: Jason A. Donenfeld <Jason@zx2c4.com>
    Date:   Wed Sep 21 11:31:34 2022 +0200

        x86: re-enable rng seeding via SetupData

    commit 3824e25db1a84fadc50b88dfbe27047aa2f7f85d
    Author: Gerd Hoffmann <kraxel@redhat.com>
    Date:   Wed Aug 17 10:39:40 2022 +0200

        x86: disable rng seeding via setup_data

Fixes: 67f7e426e5 ("hw/i386: pass RNG seed via setup_data entry")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Dov Murik <dovmurik@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>