Revert "parisc: Mark cr16 CPU clocksource unstable on all SMP machines"

This reverts commit afdb4a5b

.

It triggers RCU stalls at boot with a 32-bit kernel.

Signed-off-by: Helge Deller <deller@gmx.de>
Noticed-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # v5.16+