Add is_unranked flag to Tensors

This adds a bool field, is_unranked to TosaTensor in tosa.fbs
to indicate whether a tensor with shape = {} is an unranked tensor
or an 0-D tensor.
For older tosa files without this field, the default value is false.

Signed-off-by: Tai Ly <tai.ly@arm.com>
Change-Id: I86950050b522565509863c483cd3a3c1c50f8f69
diff --git a/schema/tosa.fbs b/schema/tosa.fbs
index 0943f11..9033351 100644
--- a/schema/tosa.fbs
+++ b/schema/tosa.fbs
@@ -282,6 +282,7 @@
   type:DType;                       // data type of the tensor
   data: [ubyte] (force_align: 8);   // raw data array if it's a constant tensor.
   variable: bool;                   // is this a variable tensor
+  is_unranked: bool;                // whether this is an unranked tensor
 }
 
 table TosaOperator {