spi: Check if transfer is mapped before calling DMA sync APIs

spi: Check if transfer is mapped before calling DMA sync APIs

The resent update to remove the orig_nents checks revealed
that not all DMA sync backends can cope with the unallocated
SG list, while supplying orig_nents == 0 (the commit 861370f49ce4
("iommu/dma: force bouncing if the size is not cacheline-aligned"),
for example, makes that happen for the IOMMU case). It means
we have to check if the buffers are DMA mapped before trying
to sync them. Re-introduce that check in a form of calling
->can_dma() in the same way as it's done in the DMA mapping loop
for the SPI transfers.

Reported-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
Closes: https://lore.kernel.org/r/8ae675b5-fcf9-4c9b-b06a-4462f70e1322@linaro.org
Closes: https://lore.kernel.org/all/d3679496-2e4e-4a7c-97ed-f193bd53af1d@notapiano
Fixes: 8cc3bad9d9d6 ("spi: Remove unneded check for orig_nents")
Suggested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://msgid.link/r/20240522171018.3362521-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>