dts: Limit search of device tree bindings to dts/bindings dir
dts: Limit search of device tree bindings to dts/bindings dir

Now that all the yaml binding files are in dts/bindings lets limit the
search path for bindings to that location.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

ldts/zephyr,galak/zephyr,nashif/zephyr,mbolivar/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,zephyrproject-rtos/zephyr,fbsder/zephyr,Vudentz/zephyr,kraj/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,fbsder/zephyr,nashif/zephyr,Vudentz/zephyr,zephyriot/zephyr,finikorg/zephyr,punitvara/zephyr,mbolivar/zephyr,kraj/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,aceofall/zephyr-iotos,ldts/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,finikorg/zephyr,finikorg/zephyr,zephyriot/zephyr,aceofall/zephyr-iotos,punitvara/zephyr,aceofall/zephyr-iotos,punitvara/zephyr,Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,kraj/zephyr,galak/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,fbsder/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,fbsder/zephyr,zephyriot/zephyr,explora26/zephyr,galak/zephyr,kraj/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,galak/zephyr,fbsder/zephyr,nashif/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,mbolivar/zephyr,explora26/zephyr,finikorg/zephyr,zephyriot/zephyr,Vudentz/zephyr