staging: axis-fifo: Add elaborate description in Kconfig

- The Xilinx AXI-Stream FIFO IP core driver description is elaborated.
  - References: Xilinx PG080 document, axis-fifo.txt

Signed-off-by: Moses Christopher <moseschristopherb@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/axis-fifo/Kconfig

@@ -7,5 +7,7 @@ config XIL_AXIS_FIFO
 	depends on OF
 	default n
 	help
-	  This adds support for the Xilinx AXI-Stream
-	  FIFO IP core driver.
+	  This adds support for the Xilinx AXI-Stream FIFO IP core driver.
+	  The AXI Streaming FIFO allows memory mapped access to a AXI Streaming
+	  interface. The Xilinx AXI-Stream FIFO IP core can be used to interface
+	  to the AXI Ethernet without the need to use DMA.