dmaengine: Fix dma_async_tx_descriptor->tx_submit documentation

Commit 790fb9956eea ("linux/dmaengine.h: fix a few kernel-doc
warnings") inserted new documentation for @desc_free in the middle of
@tx_submit's description.

Put @tx_submit's description back together, matching the indentation
style of the rest of the documentation for dma_async_tx_descriptor.

Fixes: 790fb9956eea ("linux/dmaengine.h: fix a few kernel-doc warnings")
Reviewed-by: Dave Jiang <[e-mail]>
Signed-off-by: Nathan Lynch <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

include/linux/dmaengine.h

···
  * @phys: physical address of the descriptor
  * @chan: target channel for this operation
  * @tx_submit: accept the descriptor, assign ordered cookie and mark the
+ *	descriptor pending. To be pushed on .issue_pending() call
  * @desc_free: driver's callback function to free a resusable descriptor
  *	after completion
- * descriptor pending. To be pushed on .issue_pending() call
  * @callback: routine to call after this operation is complete
  * @callback_result: error result from a DMA transaction
  * @callback_param: general parameter to pass to the callback routine