bootmeth_efi: Check the filename-allocation in the network path

If the filename cannot be set we should give up. Add the missing error
check.

Signed-off-by: Simon Glass <sjg@chromium.org>

boot/bootmeth_efi.c

@@ -252,6 +252,8 @@ static int distro_efi_read_bootflow_net(struct bootflow *bflow)
 	if (!bootfile_name)
 		return log_msg_ret("bootfile_name", ret);
 	bflow->fname = strdup(bootfile_name);
+	if (!bflow->fname)
+		return log_msg_ret("fi0", -ENOMEM);
 
 	/* do the hideous EFI hack */
 	efi_set_bootdev("Net", "", bflow->fname, map_sysmem(addr, 0),