Use latest version of afb-helpers submodule.

Changes of afb-helpers:

(52f0478 - Jonathan Aillet) Remove unnecessary 'AFB_DEBUG' redefinition
(fc1c62a - Jonathan Aillet) Use binding version to handle dynapi
(5811a53 - Jonathan Aillet) At search, use the prefix parameter as a prefix
(2c29f15 - Loïc Collignon) Remove deprecated use of cmake/Qt macro
(5bec8c5 - Loïc Collignon) Rename method to avoid conflict with Qt's one

Change-Id: Ief77446c27e4c6299c1ba3e82d42a35ecf798e7f
Signed-off-by: Loïc Collignon <loic.collignon@iot.bzh>

diff --git a/afb-helpers b/afb-helpers
index 43ec971..52f0478 160000 (submodule)
--- a/afb-helpers
+++ b/afb-helpers
@@ -1 +1 @@
-Subproject commit 43ec9716bf83d8a6e5ff15909705cb1adc3c1892
+Subproject commit 52f04783535948f2782780992710276f3419e56e