drm/xe: Change the name of frequency sysfs attributes

Switching the names of frequency sysfs attrbutes to align with
required devfreq changes. The name changes are as below;

-freq_act -> act_freq
-freq_cur -> cur_freq
-freq_rpn -> rpn_freq
-freq_rpe -> rpe_freq
-freq_rp0 -> rp0_freq
-freq_min -> min_freq
-freq_max -> max_freq

Signed-off-by: Sujaritha Sundaresan <sujaritha.sundaresan@intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>