Blackfin serial driver Kconfig: depend on DMA not being enabled rather than a specific DMA size

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

drivers/serial/Kconfig

@@ -624,7 +624,7 @@ choice
 
 config SERIAL_BFIN_DMA
 	bool "DMA mode"
-	depends on DMA_UNCACHED_1M && !KGDB_UART
+	depends on !DMA_UNCACHED_NONE && !KGDB_UART
 	help
 	  This driver works under DMA mode. If this option is selected, the
 	  blackfin simple dma driver is also enabled.