[MLIR][TORCH] Add support for none result for convolution_backward op (#4063)

This commit adds the support for handling the cases when any result of
the convolution backward op is none.

This commit also adds the support for handling none results in
SimplifyShapeCalculations pass.

Signed-off-by: Vivek Khandelwal <[email protected]>

Author: vivekkhandelwal1