ACPI, x86: fix Dell M6600 ACPI reboot regression via DMI

commit 76eb9a30db4bc8fd172f9155247264b5f2686d7b upstream.

Dell Precision M6600 is known to require PCI reboot, so add it to
the reboot blacklist in pci_reboot_dmi_table[].

https://bugzilla.kernel.org/show_bug.cgi?id=42749

cc: x86@kernel.org
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>