scripts: parse_syscalls: Multiplatform separators
scripts: parse_syscalls: Multiplatform separators

In order to support both "/" and "\" as OS path separators,
use the correct Python os.sep helper.

Signed-off-by: Carles Cufi <853081dc8dca4fe6a7e3c984752718b5db36e060@nordicsemi.no>

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