[configs] Enable virtio rng driver

TEST=Boot image on vim2 & NUC, and `cat /dev/random`

Change-Id: I0fe3925eade98e17138f58bda6b607aa490c9eab
diff --git a/arch/arm64/configs/machina_defconfig b/arch/arm64/configs/machina_defconfig
index 67fa283..e6c75b6 100644
--- a/arch/arm64/configs/machina_defconfig
+++ b/arch/arm64/configs/machina_defconfig
@@ -17,6 +17,7 @@
 CONFIG_SERIAL_AMBA_PL011=y
 CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
 CONFIG_VIRTIO_CONSOLE=y
+CONFIG_HW_RANDOM_VIRTIO=y
 CONFIG_DRM=y
 CONFIG_DRM_VIRTIO_GPU=y
 CONFIG_VIRTIO_PCI=y
diff --git a/arch/x86/configs/machina_defconfig b/arch/x86/configs/machina_defconfig
index a486687..95a6498 100644
--- a/arch/x86/configs/machina_defconfig
+++ b/arch/x86/configs/machina_defconfig
@@ -20,6 +20,7 @@
 CONFIG_SERIAL_8250_NR_UARTS=1
 CONFIG_SERIAL_8250_RUNTIME_UARTS=1
 CONFIG_VIRTIO_CONSOLE=y
+CONFIG_HW_RANDOM_VIRTIO=y
 # CONFIG_PTP_1588_CLOCK is not set
 CONFIG_DRM=y
 CONFIG_DRM_VIRTIO_GPU=y