dmaengine: PL08x: constify channel names and bus_id strings

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/linux/amba/pl08x.h

@@ -58,7 +58,7 @@ enum {
  * these buses (use PL08X_AHB1 | PL08X_AHB2).
  */
 struct pl08x_channel_data {
-	char *bus_id;
+	const char *bus_id;
 	int min_signal;
 	int max_signal;
 	u32 muxval;