brcmsmac: add support for a BCM4313 with PCI id 0x4313

There are some BCM4313 out there with a PCI id of 0x4313. These devices
are missing a sprom and are only used on routers or other embedded
devices. We found one connected to a BCM63XX SoC.

This devices was found by someone in this ticket:
https://dev.openwrt.org/ticket/13551



Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>