wifi: mwifiex: use is_zero_ether_addr() instead of ether_addr_equal()

Use is_zero_ether_addr() instead of ether_addr_equal()
to check if the ethernet address is all zeros.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Acked-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230808081023.2303423-1-ruanjinjie@huawei.com