cmake: flash: Remove fake path to zephyr_flash_debug.py
cmake: flash: Remove fake path to zephyr_flash_debug.py

We append a path to the FLASH_SCRIPT/DEBUG_SCRIPT that was bogus and not
really needed by zephyr_flash_debug.py.  So lets remove it since its
just confusing.

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

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