firewire: core: fix undefined reference error in ARM EABI

firewire: core: fix undefined reference error in ARM EABI

For ARM EABI, GCC generates a reference to __aeabi_uldivmod when compiling
a division of 64-bit integer with 32-bit integer. This function is not
available in Linux kernel. In such cases, helper macros are defined in
include/linux/math64.h.

This commit replaces the division with div_u64().

Fixes: 8ec6a8ec23b9 ("firewire: core: suppress overflow warning when computing jiffies from isochronous cycle")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509270428.FZaO2PPq-lkp@intel.com/
Link: https://lore.kernel.org/r/20250928011910.581475-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>