hw/arm/imx8mp-evk: Provide some defaults matching real hardware

Having four CPUs and 6 GiB of RAM matches real hardware. Fix the machine
defaults to make its use more ergonomic and less error-prone.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-id: 20260114213227.3812-2-shentey@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/imx8mp-evk.rst

@@ -54,7 +54,7 @@ Now that everything is prepared the machine can be started as follows:
 
 .. code-block:: bash
 
-  $ qemu-system-aarch64 -M imx8mp-evk -smp 4 -m 3G \
+  $ qemu-system-aarch64 -M imx8mp-evk \
       -display none -serial null -serial stdio \
       -kernel Image \
       -dtb imx8mp-evk.dtb \

hw/arm/imx8mp-evk.c

@@ -117,8 +117,10 @@ static void imx8mp_evk_machine_init(MachineClass *mc)
 {
     mc->desc = "NXP i.MX 8M Plus EVK Board";
     mc->init = imx8mp_evk_init;
+    mc->default_cpus = 4;
     mc->max_cpus = FSL_IMX8MP_NUM_CPUS;
     mc->default_ram_id = "imx8mp-evk.ram";
+    mc->default_ram_size = 6 * GiB;
     mc->get_default_cpu_type = imx8mp_evk_get_default_cpu_type;
 }