[PATCH] async_tx: Use the channel-switch Kconfig symbol

[Pengpeng Hou]

`ASYNC_TX_ENABLE_CHANNEL_SWITCH` is the Kconfig symbol selected by DMA
engine providers which need async_tx channel switching.

`CONFIG_ASYNC_TX_CHANNEL_SWITCH` is not generated by Kconfig.  As a
result, the DMA-engine shortcut in async_tx.h tests an impossible
configuration symbol and cannot track the provider world described by
drivers/dma/Kconfig.

Use the generated `CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH` name instead.

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 include/linux/async_tx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/async_tx.h b/include/linux/async_tx.h
--- a/include/linux/async_tx.h
+++ b/include/linux/async_tx.h
@@ -74,7 +74,7 @@ struct async_submit_ctl {
 	void *scribble;
 };
 
-#if defined(CONFIG_DMA_ENGINE) && !defined(CONFIG_ASYNC_TX_CHANNEL_SWITCH)
+#if defined(CONFIG_DMA_ENGINE) && !defined(CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH)
 #define async_tx_issue_pending_all dma_issue_pending_all
 
 /**