staging: brcm80211: move brcmf_mmc_suspend to sdio layer in fullmac

brcmf_mmc_suspend is used for sdio suspend/resume function. Hence it
should be placed in sdio interface layer.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>