Revert "usb: dwc3: gadget: Fix OTG events when gadget driver isn't loaded"

This reverts commit df4a6a26.

This is a preparation change for merging android-4.14.111 into
msm-4.14 branch.

This change was introduced for SNPS core configured for OTG 2.0
only, which does not hold true for qcom socs. It leads to
unclocked register access.

Change-Id: I21394f10b4192485ee1aa8fdb762b715e71ec722
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>