drivers: usb: gadget: Backport from caf-jb_mr1_chocolate

Change-Id: Ida5fd7b4f3ab48fee26a5090b39efad61c1f82b2
disable CONFIG_DEBUG_FS and open the pandora's box
While fixing the mess spilled out of the box,
all code changes are my fault, don't blame anyone else :)
To the devs who made this mess:
A kernel option is an option, you must know that it can be disabled.
If you need a kernel option, declare a dependence in one of the Kconfig files.
Otherwise, put your "professional" coding together
and handle the optional kernel features properly.
DEBUG_FS is not your scratch pad.
Sheesh!
-mrg666

Change-Id: I1f3aabd0f50f7f3287209eec1c4af04bfd3174aa
vigor: fix compile

Change-Id: I333123a448b186ebc47d1a4cc703c4ddcaabc481