Revert "usb: dwc3: gadget: introduce cancelled_list"

This reverts commit bba5f987.

This is a preparation change for merging android-4.19.57 into
msm-4.19 branch.

Reverted due to BootTimeRunner regression.

Change-Id: I07e4cfa0f995459e1b89d20b64b5f0075ced1b64
Signed-off-by: Ivaylo Georgiev <irgeorgiev@codeaurora.org>