brcmfmac: streamline SDIO read frame routine

SDIO read non-glomming frame routine handles first frame and
follow up frame read separately. But they share a lot of common
code. This patch abstracts a brcmf_sdio_hdparser function and
optimize the code flow for better readability and future
optimization.

Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>