drm/amd/pm: Remove power2_average node

drm/amd/pm: Remove power2_average node

SOC power consumption is reported by power1_average.
power2_cap_default/min/max only represent second level limits
and don't represent a different type of power or power consumption
by a subsection of the SOC. Therefore power2_average does not serve any
purpose and hence removing power2_average sysfs node

Signed-off-by: Asad Kamal <asad.kamal@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>