MESACI: Build etnaviv as a module

Otherwise, the VIM3 boards hang during boot, probably due to a spike in
power usage when both the GPU, DPU and NPU are probed.

kernel/configs/mesa3d-ci_arm64.config

@@ -22,7 +22,7 @@ CONFIG_DRM_LIMA=y
 CONFIG_DRM_PANEL_SIMPLE=y
 CONFIG_DRM_PANEL_EDP=y
 CONFIG_DRM_MSM=y
-CONFIG_DRM_ETNAVIV=y
+CONFIG_DRM_ETNAVIV=m
 CONFIG_DRM_I2C_ADV7511=y
 CONFIG_PWM_CROS_EC=y
 CONFIG_BACKLIGHT_CLASS_DEVICE=y