drm/i915/tgl/perf: use the same oa ctx_id format as icl

Compared to Icelake, Tigerlake's MAX_CONTEXT_HW_ID is smaller by one, but
since we just use the upper 32 bits of the lrc_desc, it's guaranteed OA
will use the correct one.

Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190823082055.5992-19-lucas.demarchi@intel.com