fddi: defza: add missing pointer type cast

hw_addr is a uint AKA unsigned int. dev_addr_set() takes
a u8 *.

  drivers/net/fddi/defza.c:1383:27: error: passing argument 2 of 'dev_addr_set' from incompatible pointer type [-Werror=incompatible-pointer-types]

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 1e9258c3

 ("fddi: defxx,defza: use dev_addr_set()")
Acked-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20211025160000.2803818-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>