b43/legacy: Remove firmware IDs

This removes the "FWxx" ID strings from the b43 and b43legacy
drivers. They were once used to match a specific driver revision
to a set of firmware files. However, this is hardly useful today.
Additionally, the IDs are not updated and maintained properly, so
they might mislead users.

Signed-off-by: Michael Buesch <m@bues.ch>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>