tools/power/turbostat: Add support for new i915 sysfs knobs

tools/power/turbostat: Add support for new i915 sysfs knobs

On Meteorlake platform, i915 driver supports the traditional graphics
sysfs knobs including
   /sys/class/drm/card0/power/rc6_residency_ms
   /sys/class/drm/card0/gt_cur_freq_mhz
   /sys/class/drm/card0/gt_act_freq_mhz

At the same time, it also supports
   /sys/class/drm/card0/gt/gt0/rc6_residency_ms
   /sys/class/drm/card0/gt/gt0/rps_cur_freq_mhz
   /sys/class/drm/card0/gt/gt0/rps_act_freq_mhz
   /sys/class/drm/card0/gt/gt1/rc6_residency_ms
   /sys/class/drm/card0/gt/gt1/rps_cur_freq_mhz
   /sys/class/drm/card0/gt/gt1/rps_act_freq_mhz
gt0 is for GFX and gt1 is for SA Media.

Enhance turbostat to prefer the i915 new sysfs knobs.
Export gt0 via BIC_GFX_rc6/BIC_GFXMHz/BIC_GFXACTMHz.
Export gt1 via BIC_SMA_mc6/BIC_SMAMHz/BIC_SMAACTMHz.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>