qemu: arm: Initialise virtio devices in board_late_init

On the qemu arm platform, the virtio devices are initialised in the
board_init function, which gets called before the initr_pci. With
this sequence, the virtio block devices on the pci bus are not
initialised. Move the initialisation of the virtio devices to
board_late_init which gets called after the call to initr_pci.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>

board/emulation/qemu-arm/qemu-arm.c

@@ -64,6 +64,11 @@ struct mm_region *mem_map = qemu_arm64_mem_map;
 #endif
 
 int board_init(void)
+{
+	return 0;
+}
+
+int board_late_init(void)
 {
 	/*
 	 * Make sure virtio bus is enumerated so that peripherals