[CodeGen] Fix invalid shift in mul expansion

Summary: When expanding mul in type legalization make sure the type for shift amount can actually fit the value. This fixes PR30354 https://llvm.org/bugs/show_bug.cgi?id=30354.

Reviewers: hfinkel, majnemer, RKSimon

Subscribers: RKSimon, llvm-commits

Differential Revision: https://reviews.llvm.org/D24478

llvm-svn: 281403