ARM: 9416/1: amba: make amba_bustype constant

Since commit d492cc25 ("driver core: device.h: make struct
bus_type a const *"), the driver core can properly handle constant
struct bus_type, move the amba_bustype variable to be a constant
structure as well, placing it into read-only memory which can not be
modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

drivers/amba/bus.c

@@ -435,7 +435,7 @@ static const struct dev_pm_ops amba_pm = {
  * DMA configuration for platform and AMBA bus is same. So here we reuse
  * platform's DMA config routine.
  */
-struct bus_type amba_bustype = {
+const struct bus_type amba_bustype = {
 	.name		= "amba",
 	.dev_groups	= amba_dev_groups,
 	.match		= amba_match,

include/linux/amba/bus.h

@@ -105,7 +105,7 @@ enum amba_vendor {
 	AMBA_VENDOR_LSI = 0xb6,
 };
 
-extern struct bus_type amba_bustype;
+extern const struct bus_type amba_bustype;
 
 #define to_amba_device(d)	container_of_const(d, struct amba_device, dev)