x86/reboot: Skip DMI checks if reboot set by user

Skip DMI checks for vendor specific reboot quirks if the user
passed in a reboot= arg on the command line - we should never
override user choices.

Signed-off-by: Michael D Labriola <michael.d.labriola@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Michael D Labriola <mlabriol@gdeb.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/87wr8ab9od.fsf@gmail.com


Signed-off-by: Ingo Molnar <mingo@elte.hu>