i3c: master: Add helpers for DMA mapping and bounce buffer handling

i3c: master: Add helpers for DMA mapping and bounce buffer handling

Some I3C controllers such as MIPI I3C HCI may pad the last DWORD (32-bit)
with stale data from the RX FIFO in DMA transfers if the receive length
is not DWORD aligned and when the device DMA is IOMMU mapped.

In such a case, a properly sized bounce buffer is required in order to
avoid possible data corruption. In a review discussion, proposal was to
have a common helpers in I3C core for DMA mapping and bounce buffer
handling.

Drivers may use the helper i3c_master_dma_map_single() to map a buffer
for a DMA transfer. It internally allocates a bounce buffer if buffer is
not DMA'able or when the driver requires it for a transfer.

Helper i3c_master_dma_unmap_single() does the needed cleanups and
data copying from the bounce buffer.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250822105630.2820009-2-jarkko.nikula@linux.intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>