parisc: remove big kernel lock

The parisc version of the perf code is sufficiently
protected by its own spinlock, no need to use the BKL.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org