spi: Rework per message DMA mapped flag to be per transfer

spi: Rework per message DMA mapped flag to be per transfer

The granularity of DMA mappings is transfer and moreover,
the direction is also important as it can be unidirect.

The current cur_msg_mapped flag doesn't fit well the DMA mapping
and syncing calls and we have tons of checks around on top of it.
So, instead of doing that rework the code to use per transfer per
direction flag to show if it's DMA mapped or not.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
Link: https://lore.kernel.org/r/20240531194723.1761567-9-andriy.shevchenko@linux.intel.com
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>