parisc: Fix mask used to select futex spinlock

The address bits used to select the futex spinlock need to match those used in
the LWS code in syscall.S. The mask 0x3f8 only selects 7 bits.  It should
select 8 bits.

This change fixes the glibc nptl/tst-cond24 and nptl/tst-cond25 tests.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Fixes: 53a42b63

 ("parisc: Switch to more fine grained lws locks")
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Helge Deller <deller@gmx.de>