linux/dmaengine.h: fix a few kernel-doc warnings

The comment block for "Interleaved Transfer Request" should not begin
with "/**" since it is not in kernel-doc format.

Fix doc name for enum sum_check_flags.

Fix all (4) missing struct member warnings.

Use "Warning:" for one "Note:" in enum dma_desc_metadata_mode since
scripts/kernel-doc does not allow more than one Note:
per function or identifier description.

This leaves around 49 kernel-doc warnings like:
  include/linux/dmaengine.h:43: warning: Enum value 'DMA_OUT_OF_ORDER' not described in enum 'dma_status'

and another scripts/kernel-doc problem with it not being able to parse
some typedefs.

Fixes: b14dab79 ("DMAEngine: Define interleaved transfer request api")
Fixes: ad283ea4 ("async_tx: add sum check flags")
Fixes: 27242021 ("dmaengine: Add DMA_CTRL_REUSE")
Fixes: f067025b ("dmaengine: add support to provide error result from a DMA transation")
Fixes: d38a8c62 ("dmaengine: prepare for generic 'unmap' data")
Fixes: 5878853f ("dmaengine: Add API function dmaengine_prep_peripheral_dma_vec()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Nuno Sa <nuno.sa@analog.com>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: dmaengine@vger.kernel.org
Link: https://lore.kernel.org/r/20241202172004.76020-1-rdunlap@infradead.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>