hw/i386: remove obsolete manual deprecation reason string of i440fx machines

hw/i386: remove obsolete manual deprecation reason string of i440fx machines

The automatic deprecation mechanism introduced in the preceeding patches
will mark every i440fx machine upto and including 2.12 as deprecated. As
such we can revert the manually added deprecation introduced in:

  commit 792b4fdd4eb8197bd6eb9e80a1dfaf0cb3b54aeb
  Author: Philippe Mathieu-Daudé <philmd@linaro.org>
  Date:   Wed Feb 28 10:34:35 2024 +0100

    hw/i386/pc: Deprecate 2.4 to 2.12 pc-i440fx machines

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240620165742.1711389-14-berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>