[mlir][tosa] Align operator descriptions with the spec

This commit aligns the operator descriptions to the v1.0
spec.

Change-Id: I4774faa861e04748d411ba99fe61fe5d28475bc4
Co-authored-by: Peng Sun <[email protected]>
Signed-off-by: Luke Hutton <[email protected]>

Author: 2 people