b43: N-PHY: define registers names for 2056 radio

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Cc: Henry Ptasinski <henryp@broadcom.com>
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Nohee Ko <noheek@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>