b43: ensue that BCMA is "y" when B43 is "y"

When b43 gets build into the kernel and it should use bcma we have to
ensure that bcma was also build into the kernel and not as a module.
In this patch this is also done for SSB, although you can not
build b43 without ssb support for now.

This fixes a build problem reported by Randy Dunlap in
5187EB95.2060605@infradead.org

Reported-By: Randy Dunlap <rdunlap@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>