i386: replace g_malloc()+memcpy() with g_memdup()

I found these pattern via grepping the source tree. I don't have a
coccinelle script for it!
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

hw/i386/multiboot.c

@@ -352,8 +352,7 @@ int load_multiboot(FWCfgState *fw_cfg,
     mb_debug("           mb_mods_count = %d\n", mbs.mb_mods_count);
 
     /* save bootinfo off the stack */
-    mb_bootinfo_data = g_malloc(sizeof(bootinfo));
-    memcpy(mb_bootinfo_data, bootinfo, sizeof(bootinfo));
+    mb_bootinfo_data = g_memdup(bootinfo, sizeof(bootinfo));
 
     /* Pass variables to option rom */
     fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ENTRY, mh_entry_addr);