Rename quantized data types to remove ambiguity for signed/unsigned payloads

!android-nn-driver:2572

Change-Id: I8fe52ceb09987b3d05c539409510f535165455cc
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/armnnSerializer/ArmnnSchema.fbs b/src/armnnSerializer/ArmnnSchema.fbs
index bad95cf..0d30d96 100644
--- a/src/armnnSerializer/ArmnnSchema.fbs
+++ b/src/armnnSerializer/ArmnnSchema.fbs
@@ -30,10 +30,12 @@
 enum DataType : byte {
     Float16 = 0,
     Float32 = 1,
-    QuantisedAsymm8 = 2,
+    QuantisedAsymm8 = 2, // deprecated
     Signed32 = 3,
     Boolean = 4,
-    QuantisedSymm16 = 5
+    QuantisedSymm16 = 5, // deprecated
+    QAsymmU8 = 6,
+    QSymmS16 = 7
 }
 
 enum DataLayout : byte {