scripts: cleanup unwanted updstreamed file
scripts: cleanup unwanted updstreamed file

scripts/dts_sanity/edts_ref.json_save has been pushed by error
in commmit a429104095fae1a2e19533644bc48baa99a5ce26
Clean it up.

Signed-off-by: Erwan Gouriou <de4d967452b83bb0e37525652734e7d9163b6a4c@linaro.org>

galak/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,ldts/zephyr,finikorg/zephyr,explora26/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,Vudentz/zephyr,explora26/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,punitvara/zephyr,nashif/zephyr,galak/zephyr,explora26/zephyr,ldts/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,ldts/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,nashif/zephyr,explora26/zephyr