brcmfmac: use different error value for invalid ram base address

The function brcmf_chip_tcm_rambase() returns 0 as invalid ram base
address. However, upcoming chips have ram base address starting at
zero so we have to find a more appropriate invalid value to return.

Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1627505434-9544-2-git-send-email-arend.vanspriel@broadcom.com