With the new __counted_by annocation, the "sglen" struct member must
be set before accessing the "sg" array. This initialization was done in
other places where a new struct omap_desc is allocated, but these cases
were missed. Set "sglen" after allocation.

Fixes: b8517861 ("dmaengine: ti: omap-dma: Annotate struct omap_desc with __counted_by")
Signed-off-by: Kees Cook <kees@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20240716215702.work.802-kees@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>