i40e: fix build warning in ice_fltr_add_mac_to_list()

Not upstream as this was fixed in a much larger change in commit
5e24d598 ("ice: Use int for ice_status")

The function ice_fltr_add_mac_to_list() has the wrong prototype match
from the .h file to the .c declaration, so fix it up, otherwise gcc-13
complains (rightfully) that the type is incorrect.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>