bcma: add constants for chip ids

The chip IDs are used all over bcma and no constants where defined.
This patch adds the constants and makes bcma use them.

Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>