[ARM32/RyuJIT] Enable passing struct argument that use stack only (dotnet/coreclr...

[ARM32/RyuJIT] Enable passing struct argument that use stack only (dotnet/coreclr#11541)

* [ARM32/RyuJIT] Enable passing struct argument that use stack only

Enable passing struct argument when it uses stack only.
Cannot pass splitted struct argument that uses stack and register(s) yet.

* Remove redundant GC type assignment and fix internal register count

- Remove redundant GC type assignment in genPutArgStk
- Fix internal register count for ARM32: 2 -> 1

Commit migrated from https://github.com/dotnet/coreclr/commit/4349824ed5da261f408042a6a023e080ff3e71db