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>

Author: Jean-Michel Hautbois

arch/m68k/kernel/setup_mm.c

@@ -249,7 +249,11 @@ void __init setup_arch(char **cmdline_p)
 	process_uboot_commandline(&m68k_command_line[0], CL_SIZE);
 	*cmdline_p = m68k_command_line;
 	memcpy(boot_command_line, *cmdline_p, CL_SIZE);
-
+	/*
+	 * Initialise the static keys early as they may be enabled by the
+	 * cpufeature code and early parameters.
+	 */
+	jump_label_init();
 	parse_early_param();
 
 	switch (m68k_machtype) {