usb: xhci: dbc: Don't free all memory with spinlock held

The xhci debug capability (DbC) feature did its memory cleanup with
spinlock held. dma_free_coherent() warns if called with interrupts
disabled

move the memory cleanup outside the spinlock

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>