[mlir][tosa] Switch zero point of avgpool2d to input variable type (#128983)
This commit changes the TOSA operator AvgPool2d's zero point attributes
to inputs to align with TOSA 1.0 spec.
Signed-off-by: Luke Hutton <luke.hutton@arm.com>
Co-authored-by: Luke Hutton <luke.hutton@arm.com>