USB: Remove unused LPM variable.

hub_initiated_lpm_disable_count is not used by any code, so remove it.

This commit should be backported to kernels as old as 3.5, that contain
the commit 8306095fd2c1100e8244c09bf560f97aca5a311d "USB: Disable USB
3.0 LPM in critical sections."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

include/linux/usb.h

@@ -561,7 +561,6 @@ struct usb_device {
 	struct usb3_lpm_parameters u1_params;
 	struct usb3_lpm_parameters u2_params;
 	unsigned lpm_disable_count;
-	unsigned hub_initiated_lpm_disable_count;
 };
 #define	to_usb_device(d) container_of(d, struct usb_device, dev)