[mlir][tosa] Quantized tosa.avg_pool2d lowering to linalg

Includes the quantized version of average pool lowering to linalg dialect.
This includes a lit test for the transform. It is not 100% correct as the
multiplier / shift should be done in i64 however this is negligable rounding
difference.

Reviewed By: NatashaKnk

Differential Revision: https://reviews.llvm.org/D108676