usb: dwc3: Avoid store doorbell address if run/stop is cleared

Since ipa_work_handler runs in workqueue context there is a
possiblity that store doorbell address can  happen even after
run/stop is cleared which may lead to SMMU fault. Avoid this by
adding a check for pullups_connected before storing doorbell
address.

Change-Id: I933d6972aa9c6077481e0bdb56a5ca22a1c57e55
Signed-off-by: Pratham Pratap <prathampratap@codeaurora.org>