[mlir][linalg] Add canonicalizers for depthwise conv

There are two main versions of depthwise conv depending whether the multiplier
is 1 or not. In cases where m == 1 we should use the version without the
multiplier channel as it can perform greater optimization.

Add lowering for the quantized/float versions to have a multiplier of one.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D108959