b43legacy: drop invalid IMCFGLO workaround

We were performing it on wrong core, it was outdated and is already
implemented in ssb.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>