b43legacy: Declare all possible ucodeX.fw files

Enhance module information with the names of the firmware files
that could be used by this driver. This helps tools like Jockey to
correctly detect and/or install the firmware files relevant to
this driver.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>