Fix incorrect assignment of READYTORUN_HELPER_[Dbl|Flt][Rem/Round] (dotnet/coreclr...

Fix incorrect assignment of READYTORUN_HELPER_[Dbl|Flt][Rem/Round] (dotnet/coreclr#21836)

Turns out there's a long-standing typo in CoreCLR that reverses
the helper enumeration values for DBL and FLT. This doesn't seem
to be a problem in the CoreCLR repo as such because it solely
uses the legacy identifiers CORINFO_HELP_DBLREM et al. We have
however ported the incorrect helper enumeration values into R2RDump
and ILCompiler. This change immediately fixes R2RDump as it resides
in the same repo, I'll send out the ILCompiler change in
a separate PR.

Commit migrated from https://github.com/dotnet/coreclr/commit/bcbb84df02d73a89dd13ea7fa2257f542202dd81