shared/gatt-helpers: Fix find by type response handling

Due to regression from

db24bf0 shared/gatt-helper: Consolidate error checking,

procedure Discover Primary Services by Service UUID, can succeed
only when last response is Error Response with ATTRIBUTE_NOT_FOUND
error code.

With this patch it also succeed when Find By Type response contains
service which is already in a required search range.

It is verified with unit test /TP/GAD/CL/BV-02-C-1-alternative
diff --git a/src/shared/gatt-helpers.c b/src/shared/gatt-helpers.c
index a0a5b26..6b39bb1 100644
--- a/src/shared/gatt-helpers.c
+++ b/src/shared/gatt-helpers.c
@@ -797,7 +797,7 @@
 		goto done;
 	}
 
-	success = false;
+	success = true;
 
 done:
 	discovery_op_complete(op, success, att_ecode);