usb: dwc3: handle pending unaligned Control OUT data phase correctly

When DWC3_EP_PENDING_REQUEST flag is set for a Control OUT Data
phase transfer, we would be missing the proper handling for
unaligned OUT requests, thus hanging a transfer.

Since proper handling is already done on dwc3_ep0_do_control_data(),
we simply re-factor that function so it can be re-used from
__dwc3_gadget_ep0_queue().

Reported-by: Pratyush Anand <pratyush.anand@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>