x86/shutdown: use ACPI reboot method for Dell PowerEdge R540

x86/shutdown: use ACPI reboot method for Dell PowerEdge R540

When EFI booting the Dell PowerEdge R540 it consistently wanders into
the weeds and gets an invalid opcode in the EFI ResetSystem call. This
is the same bug which affects the PowerEdge R740 so fix it in the same
way: quirk this hardware to use the ACPI reboot method instead.

BIOS Information
    Vendor: Dell Inc.
    Version: 1.3.7
    Release Date: 02/09/2018
System Information
    Manufacturer: Dell Inc.
    Product Name: PowerEdge R540

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>