biosemu: Do not free vga_info->BIOSImage when it is 0xc0000

For x86, vga_info->BIOSImage points to 0xc0000 which cannot be freed.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/bios_emulator/atibios.c

@@ -502,7 +502,8 @@ int biosemu_run(pci_dev_t pcidev, uchar *bios_rom, int bios_len,
 	*/
 	if (clean_up) {
 		BE_exit();
-		if (vga_info->BIOSImage)
+		if (vga_info->BIOSImage &&
+		    (u32)(vga_info->BIOSImage) != 0xc0000)
 			free(vga_info->BIOSImage);
 		free(vga_info);
 		vga_info = NULL;