[MLIR][affine] Prevent fusion when ops with memory effect free are present...

[MLIR][affine] Prevent fusion when ops with memory effect free are present between producer and consumer

This commit fixes a bug in affine fusion pipeline where an
incorrect fusion is performed despite a dealloc op is present
between a producer and a consumer. This is done by creating a
node for dealloc op in the MDG.

Reviewed By: bondhugula, dcaballe

Differential Revision: https://reviews.llvm.org/D97032