Revert "usb: gadget: Add check gadget function bind or not"

This reverts commit fbbccfe9d3d66aa791177cdce0af9c5d0ace99a5.

Remove opts->bound check from configfs node show/store operations
in order to make them usable.

Change-Id: Iac2c46899b02a8c3a55a04929108d4d65e880869
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>