ethernet: sis900: fix indentation

A space has snuck in.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 74fad215 ("ethernet: sis900: use eth_hw_addr_set()")
Link: https://lore.kernel.org/r/20211111210824.676201-1-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>