ppc: qemu: Enable OF_CONTROL

The QEMU ppce500 machine generates a device tree blob and passes
it to U-Boot during boot. Let's enable OF_CONTROL with OF_BOARD
and provide board_fdt_blob_setup() in the board codes.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

board/freescale/qemu-ppce500/qemu-ppce500.c

@@ -364,3 +364,13 @@ u32 cpu_mask(void)
 {
 	return (1 << cpu_numcores()) - 1;
 }
+
+/**
+ * Return the virtual address of FDT that was passed by QEMU
+ *
+ * @return virtual address of FDT received from QEMU in r3 register
+ */
+void *board_fdt_blob_setup(void)
+{
+	return get_fdt_virt();
+}