m68k: Initialize jump labels early during setup_arch()

When using static keys early, e.g. by specifying "thread_backlog_napi"
on the kernel command line:

    WARNING: CPU: 0 PID: 0 at include/linux/jump_label.h:322 setup_backlog_napi_threads+0x40/0xa0
    static_key_enable(): static key '0x5ceec0' used before call to jump_label_init()

The function jump_label_init() should be called from setup_arch() very
early for proper functioning of jump label support.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/20241016-fix-jump-label-v1-1-eb74c5f68405@yoseli.org


[geert: Add reproducer]
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>