Revert "USB: Debugfs: Fix compilation issues when debugfs is disabled"

This reverts commit 1eb4c9cb.
There is a bug in this change that causes a crash when
gbam_cleanup() is called multiple times.

Change-Id: Ic5f8b8168bbaa52f3417812a268097c23f6e7514
Signed-off-by: Jack Pham <jackp@codeaurora.org>