USB core: Use const where possible.

This patch marks some USB core's functions parameters as const. This
improves the design (we're saying to the caller that its parameter is
not going to be modified) and may help in compiler's optimisation work.

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 82837d4..4eb98eb 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -67,7 +67,8 @@
  * Don't call this function unless you are bound to one of the interfaces
  * on this device or you have locked the device!
  */
-struct usb_interface *usb_ifnum_to_if(struct usb_device *dev, unsigned ifnum)
+struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,
+				      unsigned ifnum)
 {
 	struct usb_host_config *config = dev->actconfig;
 	int i;
@@ -100,8 +101,8 @@
  * Don't call this function unless you are bound to the intf interface
  * or you have locked the device!
  */
-struct usb_host_interface *usb_altnum_to_altsetting(struct usb_interface *intf,
-		unsigned int altnum)
+struct usb_host_interface *usb_altnum_to_altsetting(const struct usb_interface *intf,
+						    unsigned int altnum)
 {
 	int i;
 
@@ -356,7 +357,7 @@
  * case the driver already owns the device lock.)
  */
 int usb_lock_device_for_reset(struct usb_device *udev,
-		struct usb_interface *iface)
+			      const struct usb_interface *iface)
 {
 	unsigned long jiffies_expire = jiffies + HZ;
 
@@ -852,8 +853,8 @@
  *
  * Reverse the effect of this call with usb_buffer_unmap_sg().
  */
-int usb_buffer_map_sg (struct usb_device *dev, unsigned pipe,
-		struct scatterlist *sg, int nents)
+int usb_buffer_map_sg(const struct usb_device *dev, unsigned pipe,
+		      struct scatterlist *sg, int nents)
 {
 	struct usb_bus		*bus;
 	struct device		*controller;
@@ -887,8 +888,8 @@
  * Use this when you are re-using a scatterlist's data buffers for
  * another USB request.
  */
-void usb_buffer_dmasync_sg (struct usb_device *dev, unsigned pipe,
-		struct scatterlist *sg, int n_hw_ents)
+void usb_buffer_dmasync_sg(const struct usb_device *dev, unsigned pipe,
+			   struct scatterlist *sg, int n_hw_ents)
 {
 	struct usb_bus		*bus;
 	struct device		*controller;
@@ -913,8 +914,8 @@
  *
  * Reverses the effect of usb_buffer_map_sg().
  */
-void usb_buffer_unmap_sg (struct usb_device *dev, unsigned pipe,
-		struct scatterlist *sg, int n_hw_ents)
+void usb_buffer_unmap_sg(const struct usb_device *dev, unsigned pipe,
+			 struct scatterlist *sg, int n_hw_ents)
 {
 	struct usb_bus		*bus;
 	struct device		*controller;