Volume tests are all SKIP with topology v2 (grep PGA)

[marc-hb]

volume-basic-test.sh, check-volume-levels.sh and maybe others have always been testing only the controls with "PGA" in the name. According to @ranj063 , that "PGA" keyword is gone in topology v2. So these tests don't do anything any more, they just SKIP.

Example: https://sof-ci.01.org/sofpr/PR7854/build10005/devicetest all SKIP

Prototype fix and discussion:

• volume-basic-test.sh: don't skip "playback volume" controls #1068

• These volume tests are not even part of the MTL test plan at all right now https://sof-ci.01.org/sofpr/PR7854/build10004/devicetest