bcma/ssb: parse new attributes from sprom

These newly added attributes are used by brcmsmac. Now bcma should
parse all attributes used by brcmsmac out of the sprom.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Tested-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>