parisc: don't claim cpu irqs more than once

The CPU irqs (timer and IPI) are not shared and only need to be claimed once.
A mismatch error occurs if they are claimed more than once.

Signed-off-by: John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Signed-off-by: Helge Deller <deller@gmx.de>