x86/nmi: Remove the 'strange power saving mode' hint from unknown NMI handler

The

  Do you have a strange power saving mode enabled?

hint when unknown NMI happens dates back to i386 stone age, and isn't
currently really helpful.

Unknown NMIs are coming for many different reasons (broken firmware,
faulty hardware, ...) and rarely have anything to do with 'strange power
saving mode' (whatever that even is).

Just remove it as it's largerly misleading.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/nycvar.YFH.7.76.2203140924120.24795@cbobk.fhfr.pm