usb: langwell_udc: cancel pending requests when controller is suspended.

It is safer to cancel pending requests before free dTD and dQH when
controller enters suspend state.

Signed-off-by: Philippe Skowronski <philippe.skowronski@intel.com>
Signed-off-by: Hao Wu <hao.wu@intel.com>
[Switch to spin_lock_irq as suggested by Alan Stern]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>