docs: dma-api: clarify DMA addressing limitations

docs: dma-api: clarify DMA addressing limitations

Move the description of DMA mask from the documentation of dma_map_single()
to Part Ic - DMA addressing limitations and improve the wording.

Explain when a mask setting function may fail, and do not repeat this
explanation for each individual function.

Clarify which device parameters are updated by each mask setting function.

Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250627101015.1600042-7-ptesarik@suse.com