usb: dwc3: gadget: Refactor pullup()

[ Upstream commit 861c010a2ee1bc4a66d23f0da4aa22e75d8eaa24 ]

Move soft-disconnect sequence out of dwc3_gadget_pullup(). No
functional change here.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/4c0f259b17d95acaaa931f90276683a48a32fe22.1650593829.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 040f2dbd2010 ("usb: dwc3: gadget: Avoid duplicate requests to enable Run/Stop")
Signed-off-by: Sasha Levin <sashal@kernel.org>