drm/i915: Populate wm.max_level for everyone

Switch ilk+ and skl+ platforms to also setting up
wm.max_level and remove a bunch of if ladders as a result.

There will be a tiny change in the debugfs on CHV machines
that have DVFS disabled in the BIOS. Presviously debugfs
would show the latency for the DVFS level as well, but
that will no longer be the case. Which is arguably better
as that number is absolutely meaningless when DVFS can't
be enabled anyway.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230209003251.32021-1-ville.syrjala@linux.intel.com