i915/perf: Remove code to update PWR_CLK_STATE for gen12

i915/perf: Remove code to update PWR_CLK_STATE for gen12

PWR_CLK_STATE only needs to be modified up until gen11. For gen12 this
code is not applicable. Remove code to update context image with
PWR_CLK_STATE for gen12.

Fixes: 00a7f0d7155c ("drm/i915/tgl: Add perf support on TGL")
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240629005643.3050678-1-umesh.nerlige.ramappa@intel.com