radeonsi: NGG streamout fixes and other fixes, cleanups

This is a preparation for Gfx11 NGG streamout by stabilizing Gfx10 NGG streamout, which is 1/3rd of the commits.

There are a total of 9 fixes. 4 of them are for NGG streamout and 2 of them fix hangs with NGG streamout. No Gitlab issues are fixed here AFAIK.