boards: mps2_an385: Select QEMU_TARGET
boards: mps2_an385: Select QEMU_TARGET

Board can be emulated in QEMU, so select QEMU_TARGET as required for
various bits of "make run" magic to work.

Signed-off-by: Paul Sokolovsky <35cb557f011771c94f127d6fef99f804b62203f5@linaro.org>

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