Revert "fix 10x performance regression in stockcorr"

This reverts commit 2e046cd74b3173dc8472f9c57b41ed6482e3044f.
Avoid type inference problem in chol which caused a 10x slowdown in stockcorr benchmark.
Merge pull request #8751 from JuliaLang/anj/chol

Avoid type inference problem in chol which caused a 10x slowdown in stockcorr benchmark without breaking anything