batman-adv: Switch to kstrtox.h for kstrtou64

stable inclusion
from stable-v5.10.185
commit 7ce0e8b287204dd0b8c9ca001da16b8f6658ceee
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8L5XP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7ce0e8b287204dd0b8c9ca001da16b8f6658ceee



--------------------------------

commit 55207227 upstream.

The commit 4c527293 ("kernel.h: split out kstrtox() and simple_strtox()
to a separate header") moved the kstrtou64 function to a new header called
linux/kstrtox.h.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>