staging: r8712u: Replace '--help--' with 'help'

This patch replace '--help--' in Kconfig to silence checkpatch.pl
warning:
WARNING: prefer 'help' over '---help---' for new help texts
Signed-off-by: Wentao Cai <etsai042@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/Kconfig

@@ -4,14 +4,14 @@ config R8712U
 	select WIRELESS_EXT
 	select WEXT_PRIV
 	select FW_LOADER
-	---help---
-	This option adds the Realtek RTL8712 USB device such as the D-Link DWA-130.
-	If built as a module, it will be called r8712u.
+	help
+	    This option adds the Realtek RTL8712 USB device such as the D-Link DWA-130.
+	    If built as a module, it will be called r8712u.
 
 config R8712_TX_AGGR
 	bool "Realtek RTL8712U Transmit Aggregation code"
 	depends on R8712U && BROKEN
-	---help---
-	This option provides transmit aggregation for the Realtek RTL8712 USB device.
+	help
+	    This option provides transmit aggregation for the Realtek RTL8712 USB device.