b43: ssb: refuse to support more than IEEE 802.11 core

Some ancient Broadcom devices had one core per band, e.g.:
ssb: Found chip with id 0x4306, rev 0x02 and package 0x00
ssb: Core 0 found: ChipCommon (cc 0x800, rev 0x02, vendor 0x4243)
ssb: Core 1 found: IEEE 802.11 (cc 0x812, rev 0x04, vendor 0x4243)
ssb: Core 2 found: PCMCIA (cc 0x80D, rev 0x01, vendor 0x4243)
ssb: Core 3 found: V90 (cc 0x807, rev 0x01, vendor 0x4243)
ssb: Core 4 found: PCI (cc 0x804, rev 0x07, vendor 0x4243)
ssb: Core 5 found: IEEE 802.11 (cc 0x812, rev 0x04, vendor 0x4243)

This hardware model was dropped for newer devices handled by b43.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>