USB: pedantic: spelling correction in comment for ch9.h

Just noticed this during a grep, figured I might as well send it in.

From: D.J. Capelis <dev@capelis.dj>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/ch9.h

@@ -102,7 +102,7 @@
 #define USB_REQ_LOOPBACK_DATA_READ	0x16
 #define USB_REQ_SET_INTERFACE_DS	0x17
 
-/* The Link Power Mangement (LPM) ECN defines USB_REQ_TEST_AND_SET command,
+/* The Link Power Management (LPM) ECN defines USB_REQ_TEST_AND_SET command,
  * used by hubs to put ports into a new L1 suspend state, except that it
  * forgot to define its number ...
  */