boards: qemu_cortex_r5: Enable QEMU icount emulation

This commit enables the QEMU icount emulation mode for improved timing
stability.

In normal emulation mode (without icount), the emulation timing of the
TTC system timer is particularly unstable and this results in a high CI
failure rate.

For more details, refer to the issues zephyrproject-rtos#14173 and zephyrproject-rtos#22904.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

boards/arm/qemu_cortex_r5/board.cmake

@@ -9,6 +9,7 @@ set(QEMU_CPU_TYPE_${ARCH} cortex-r5)
 set(QEMU_FLAGS_${ARCH}
   -nographic
   -machine arm-generic-fdt
+  -icount shift=3,align=off,sleep=off -rtc clock=vm
   -dtb ${ZEPHYR_BASE}/boards/${ARCH}/${BOARD}/fdt-single_arch-zcu102-arm.dtb
   )