spi: bitbang: switch to the generic implementation of transfer_one_message
Change the bitbang driver to use the generic implementation of
transfer_one_message. This simplifies the bitbang driver code and
provides benefits like the statistics in the generic implementation.
Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based
router (OpenWRT with spi-ath79).
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Signed-off-by: Mark Brown <broonie@kernel.org>