Abstract brcmf_sdio_txpkt_prep and brcmf_sdio_txpkt_postp as a preparation
of chained tx packets for host side tx glomming.
Reviewed-by: NHante Meuleman <meuleman@broadcom.com>
Reviewed-by: NPieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NFranky Lin <frankyl@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>