[llvm] [DL] Invert `getTypeStoreSize` bytes-bits relationship to avoid `divideCeil` (PR #106757)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

> Does this give a compile-time improvement in practice?

Quite minor improvements: https://llvm-compile-time-tracker.com/compare.php?from=923a1c1fc348f7c30ff4726b54ed63ce403dc3ce&to=f28356e3b83cd10d9dc3fe69247fc90ab5c3d703&stat=instructions:u.

https://github.com/llvm/llvm-project/pull/106757