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

[Nikita Popov via llvm-commits]

nikic 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.

Looks pretty similar to the original regression: https://llvm-compile-time-tracker.com/compare.php?from=23c1b488fee99ac598203b6c3972be3b404dfbbe&to=bfd95a003139a8f930874b2234c3cab545d504a1&stat=instructions:u

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