dwc3: gadget: Remove pm_runtime calls from dwc3_gadget_ep_disable

There is a chance that ep_disable will be called from mass
storage function driver after usb is in LPM as ep_disable
in mass storage function driver is called in worker
thread context. Hence, Commit 589a7f885ae2 ("usb: dwc3: Don't
perform pm rt sync operations in atomic context") added
pm_runtime calls for mass storage function driver,
so that system can be resumed and then do the ep_disable
operations.

But Commit e8e83c46c5eb ("usb: gadget: f_mass_storage: Disable
eps during disconnect") has changed the implementation of
ep_disable in mass storage function driver. It is now being
called in atomic context. So there is no chance of ep_disable
being called after usb is in lpm. Hence remove the support for
pm_runtime calls in ep_disable as they are any how no-op.

Change-Id: I5bcc2572da1608b24b1fe1cf14b6f1c3918d2d7a
Signed-off-by: Rohith Kollalsi <quic_rkollals@quicinc.com>