brcmfmac: move brcmf_fws_deinit to bcdc layer

Move brcmf_fws_deinit into brcmf_proto_bcdc_detach since it is a bcdc
exclusive feature.

Signed-off-by: Franky Lin <franky.lin@broadcom.com>
Reviewed-by: Arend Van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>