Replace the use of mem_freq/4 with czclk_freq in the vlv c0 residency
calculations.

Also deal with VLV_COUNT_RANGE_HIGH which affects all RCx residency
counters. We have just enough bits to do this without intermediate
divisions.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>