8139too: fix buffer overrun in rtl8139_init_board

Fix rtl_chip_info buffer overrun when we can't identify the chip.
(i = ARRAY_SIZE (rtl_chip_info) in this case)

Signed-off-by: Denis Kirjanov <dkirjanov@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>