usb: gadget: f_fs: Remove lock is held before freeing checks

lock debugging already supports this, no need to do it explicitely.

Cc: balbi@ti.com
Cc: gregkh@linuxfoundation.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>