xtensa: fix stop_machine_cpuslocked call in patch_text

patch_text must invoke patch_text_stop_machine on all online CPUs, but
it calls stop_machine_cpuslocked with NULL cpumask. As a result only one
CPU runs patch_text_stop_machine potentially leaving stale icache
entries on other CPUs. Fix that by calling stop_machine_cpuslocked with
cpu_online_mask as the last argument.

Cc: stable@vger.kernel.org
Fixes: 64711f9a ("xtensa: implement jump_label support")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>