benchmarks: boot_time: Disable userspace for benchmarks
benchmarks: boot_time: Disable userspace for benchmarks

Disable userspace for benchmarks because it changes the KPI
numbers. It will be re-enabled once the required code is
in place.

Signed-off-by: Adithya Baglody <06b44f6fa9a97a2b955c2d2cd070279967447860@intel.com>

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