[IndVars] Pass TTI to replaceCongruentIVs

In IndVarSimplify after simplifying and extending loop IVs we call 'replaceCongruentIVs'.
This function optionally takes a TTI argument to be able to replace narrow IVs uses
with truncates of the widest one.
For some reason the TTI wasn't passed to the function, so it couldn't perform such
transform.
This patch fixes it.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D113024