dmaengine: ste_dma40: fix typo in enum documentation

s/40_command/d40_command to fix the below warning reported:

drivers/dma/ste_dma40.c:151: warning: expecting prototype for enum 40_command.
Prototype was for enum d40_command instead
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20230517064434.141091-2-vkoul@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/ste_dma40.c

@@ -136,7 +136,7 @@ static const struct stedma40_chan_cfg dma40_memcpy_conf_log = {
 };
 
 /**
- * enum 40_command - The different commands and/or statuses.
+ * enum d40_command - The different commands and/or statuses.
  *
  * @D40_DMA_STOP: DMA channel command STOP or status STOPPED,
  * @D40_DMA_RUN: The DMA channel is RUNNING of the command RUN.