Add dmaengine_prep_slave_sg_context() for consumers that need to pass
context value when preparing slave SG transfers.

This replaces direct use of the prep_slave_sg() callback context,
which is intended for DMA engine internal use only. Mark it as deprecated
in preparation for making DMA engine internals private.

The only current user is sound/soc/sprd/sprd-pcm-compress.c.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Frank Li (2):
      dmaengine: add dmaengine_prep_slave_sg_context() to wrap prep_slave_sg
      ASoC: sprd: replace direct ->device_prep*() calls with standard DMA engine API

 include/linux/dmaengine.h          | 13 +++++++++++++
 sound/soc/sprd/sprd-pcm-compress.c |  6 +++---
 sound/soc/sprd/sprd-pcm-dma.c      |  6 +++---
 3 files changed, 19 insertions(+), 6 deletions(-)
---
base-commit: 0d9d0dbf2fddcff5859d623e90ca73c4054276e1
change-id: 20260917-b4-dmaengine-prep-slave-sg-55e8653077aa

Best regards,
--  
Frank Li <Frank.Li@nxp.com>