framework/iotbus: remove wrong checking condition on iotbus_gpio_register_cb
framework/iotbus: remove wrong checking condition on iotbus_gpio_register_cb

The iotbus_gpio_register_cb has 4 arguments and user_date is an argument.
That is given to call back function as an function argument.
It can be NULL when we don't need to give data so that we should
remove checking null condition for user_data.

jeongarmy/TizenRT,chanijjani/TizenRT,davidfather/TizenRT,lokeshbv/TizenRT,btheosam/TizenRT,lokeshbv/TizenRT,jeongchanKim/TizenRT,btheosam/TizenRT,pillip8282/TizenRT,jeongchanKim/TizenRT,sunghan-chang/TizenRT,jeongchanKim/TizenRT,lokeshbv/TizenRT,chanijjani/TizenRT,pillip8282/TizenRT,jsdosa/TizenRT,junmin-kim/TizenRT,pillip8282/TizenRT,chanijjani/TizenRT,jsdosa/TizenRT,davidfather/TizenRT,an4967/TizenRT,jeongchanKim/TizenRT,an4967/TizenRT,JeonginKim/TizenRT,pillip8282/TizenRT,btheosam/TizenRT,jeongarmy/TizenRT,jsdosa/TizenRT,HONGCHAEHEE/TizenRT,jsdosa/TizenRT,jsdosa/TizenRT,sunghan-chang/TizenRT,jeongarmy/TizenRT,btheosam/TizenRT,chanijjani/TizenRT,JeonginKim/TizenRT,JeonginKim/TizenRT,pillip8282/TizenRT,an4967/TizenRT,HONGCHAEHEE/TizenRT,sunghan-chang/TizenRT,btheosam/TizenRT,jeongchanKim/TizenRT,chanijjani/TizenRT,junmin-kim/TizenRT,jsdosa/TizenRT,jeongchanKim/TizenRT,jsdosa/TizenRT,lokeshbv/TizenRT,jeongarmy/TizenRT,HONGCHAEHEE/TizenRT,jeongarmy/TizenRT,Samsung/TizenRT,lokeshbv/TizenRT,btheosam/TizenRT,sunghan-chang/TizenRT,HONGCHAEHEE/TizenRT,Samsung/TizenRT,davidfather/TizenRT,sunghan-chang/TizenRT,junmin-kim/TizenRT,pillip8282/TizenRT,davidfather/TizenRT,Samsung/TizenRT,an4967/TizenRT,chanijjani/TizenRT,davidfather/TizenRT,Samsung/TizenRT,jeongarmy/TizenRT,sunghan-chang/TizenRT,an4967/TizenRT,jeongarmy/TizenRT,an4967/TizenRT,Samsung/TizenRT,chanijjani/TizenRT,JeonginKim/TizenRT,Samsung/TizenRT,pillip8282/TizenRT,JeonginKim/TizenRT,junmin-kim/TizenRT,junmin-kim/TizenRT,an4967/TizenRT,lokeshbv/TizenRT,Samsung/TizenRT,JeonginKim/TizenRT,HONGCHAEHEE/TizenRT,junmin-kim/TizenRT,jeongchanKim/TizenRT,HONGCHAEHEE/TizenRT,junmin-kim/TizenRT,sunghan-chang/TizenRT,davidfather/TizenRT,davidfather/TizenRT