brcmfmac: allow GCI core enumuration

GCI core is needed for ULP operation. Allow GCI core enumuration with
below changes:
 - Allow GCI to be added to core list even when it doesn't have a wrapper.
 - Allow 8K address space size.
 - Don't overwrite the address value when an additional size descriptor
   is in place.

Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>