efi_loader: Make HII a config option

Heinrich ran into issues with HII and iPXE which lead to #SErrors on
his Odroid-C2 system. We definitely do not want to regress just yet,
so let's not expose the HII protocols by default.

Instead, let's make it a config option that people can play with
This way, we can stabilize the code in tree without breaking any
users.

Once someone figures out, why this breaks iPXE (probably a NULL
dereference), we can enable it by default.

Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

---

v1 -> v2:

  - Remove HII selftest as well

v2 -> v3:

  - Make config option
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index fc26d6a..f74f989 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1558,6 +1558,7 @@
 	if (ret != EFI_SUCCESS)
 		goto failure;
 
+#if CONFIG_IS_ENABLED(EFI_LOADER_HII)
 	ret = efi_add_protocol(&obj->header,
 			       &efi_guid_hii_string_protocol,
 			       (void *)&efi_hii_string);
@@ -1575,6 +1576,7 @@
 			       (void *)&efi_hii_config_routing);
 	if (ret != EFI_SUCCESS)
 		goto failure;
+#endif
 
 	return ret;
 failure: