x86: make hibernation always-possible

This commit:

  aced3cee: x86/Voyager: remove HIBERNATION Kconfig quirk

Made hibernation only available on UP - instead of making it available
on all of x86. Fix it.

Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>