ANDROID: USB: remove some EXPORT_SYMBOL_GPL() markings that are not needed

With the recent android gadget work, some symbols were exported that
really were not needed because the only caller was built into the module
with them.  Remove those exports as no one needs to call these outside
of the module itself.

Bug: 120441124
Bug: 317149848
Cc: Neill Kapron <nkapron@google.com>
Fixes: c6f183ea ("ANDROID: usb: gadget: configfs: Add Uevent to notify userspace")
Fixes: 6edae4fa ("ANDROID: usb: gadget: f_midi: Create f_midi device in android_usb class")
Change-Id: I750739ca6a9bb08d4de9fc2de6b9dcd5ffff9bc7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
[ Remove changes to android_f_midi_info.c as it has been deprecated ]
Signed-off-by: Neill Kapron <nkapron@google.com>