parisc: Switch to more fine grained lws locks

Increase the number of lws locks to 256 entries (instead of 16) and
choose lock entry based on bits 3-11 (instead of 4-7) of the relevant
address.  With this change we archieve more fine-grained locking in
futex syscalls and thus reduce the number of possible stalls.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>