boards: qemu: x86: Add an option for VirtIO Entropy device enabling

If CONFIG_ENTROPY_VIRTIO is enabled, enable `virtio-rng-pci` device
on qemu side.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>

Author: soburi

boards/qemu/x86/board.cmake

@@ -61,11 +61,16 @@ if(NOT CONFIG_X86_64 AND CONFIG_CACHE_MANAGEMENT)
   string(JOIN "," QEMU_CPU_FLAGS "${QEMU_CPU_FLAGS}" "clflush")
 endif()
 
+if(CONFIG_ENTROPY_VIRTIO)
+  set(QEMU_VIRTIO_ENTROPY_FLAGS -device virtio-rng-pci)
+endif()
+
 set(QEMU_FLAGS_${ARCH}
   -m ${QEMU_MEMORY_SIZE_MB}
   -cpu ${QEMU_CPU_TYPE_${ARCH}}${QEMU_CPU_FLAGS}
   -machine q35
   -device isa-debug-exit,iobase=0xf4,iosize=0x04
+  ${QEMU_VIRTIO_ENTROPY_FLAGS}
   ${REBOOT_FLAG}
   -nographic
   )