x86 reboot quirks: add Dell Precision WorkStation T5400

as reported in:

  "reboot=bios is mandatory on Dell T5400 server."
  http://bugzilla.kernel.org/show_bug.cgi?id=11108

add a DMI reboot quirk.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>