script: dts: Fix alias generation for reg property.
script: dts: Fix alias generation for reg property.

In case of having more than one reg, aliases would not generate
properly. Number of register at the end of define was missing.

Signed-off-by: Mieszko Mierunski <0153720f373f9fb33402fd56a3b748bfb748366c@nordicsemi.no>

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