bcma: support chipsets with PMU and GCI cores (devices)

Both cores are another exceptions. They are not accessed in a standard
way and to they don't need or have wrapping addresses.
This fixes bus scanning after finding such core.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>