staging: brcm80211: remove iovar IOV_BLOCKSIZE in brcmfmac

Iovar IOV_BLOCKSIZE code is not actually setting the sdio
function's block size. Use cur_blksize provided by mmc core where
necessary.

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