ia64: fix sparse warnings with cmpxchg() & xchg()

On IA64, new sparse's warnings where issued after fixing some __rcu
annotations in kernel/bpf/.

These new warnings are false positives and appear on IA64 because on this
architecture, the macros for cmpxchg() and xchg() make casts that ignore
sparse annotations.

This patch contains the minimal patch to fix this issue: adding a missing
cast and some missing '__force'.

Link: https://lore.kernel.org/r/20220601120013.bq5a3ynbkc3hngm5@mail
Link: https://lkml.kernel.org/r/20220605160738.79736-1-luc.vanoostenryck@gmail.com


Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>