usb: dwc3: Perform pm_runtime async op for suspend in ep_disable

The ep_disable functions uses pm_runtime_get_sync &
pm_runtime_put_sync_autosuspend to manage the dev & sysdev,
however doing auto suspend in sync context might lead to
errors on runtime framework due to the ASYNC flag not set.
When this happens, the runtime framework triggers
__might_sleep which in turn leads to a kernel panic.

Fix this by performing pm_runtime_put_autosuspend instead
of doing sync. This will set the ASYNC flag and will not go
for might_sleep check.

Change-Id: I9cff7738def5fac94d11e7648efc3602b9fe3ea6
Signed-off-by: Udipto Goswami <ugoswami@codeaurora.org>
Signed-off-by: Rohith Kollalsi <rkollals@codeaurora.org>