x86: qemu: Fix compiler warnings for 64-bit

This fixes compiler warnings for QEMU in 64-bit.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/qemu/qemu.c b/arch/x86/cpu/qemu/qemu.c
index 85e2481..7153eb2 100644
--- a/arch/x86/cpu/qemu/qemu.c
+++ b/arch/x86/cpu/qemu/qemu.c
@@ -47,7 +47,7 @@
 static void qemu_x86_fwcfg_read_entry_dma(struct fw_cfg_dma_access *dma)
 {
 	/* the DMA address register is big endian */
-	outl(cpu_to_be32((uint32_t)dma), FW_DMA_PORT_HIGH);
+	outl(cpu_to_be32((uintptr_t)dma), FW_DMA_PORT_HIGH);
 
 	while (be32_to_cpu(dma->control) & ~FW_CFG_DMA_ERROR)
 		__asm__ __volatile__ ("pause");