drm/i915/wm: clarify logging on not finding CxSR latency config

drm/i915/wm: clarify logging on not finding CxSR latency config

Clarify and unify the logging on not finding PNV CxSR latency
config.

Just let the i915->fsb_freq == 0 || i915->mem_freq == 0 case go through
the table instead of checking for it separately.

v2: Do not check for fsb == 0 || mem == 0 separately (Matt)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6333cb0675c531e971e829105f1ecfc4d71bdc6b.1718356614.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>