usb: xhci: dbc: Don't decrement runtime PM counter if DBC is not started

usb: xhci: dbc: Don't decrement runtime PM counter if DBC is not started

BugLink: https://bugs.launchpad.net/bugs/1779823
pm_runtime_put_sync() gets called everytime in xhci_dbc_stop().

If dbc is not started, this makes the runtime PM counter incorrectly
becomes 0, and calls autosuspend function. Then we'll keep seeing this:
[54664.762220] xhci_hcd 0000:00:14.0: Root hub is not suspended

So only calls pm_runtime_put_sync() when dbc was started.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 74cb319bd97dd62881f97ea5a3228f7c2546bf56 git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-linus)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>