drm/xe: Only request PCODE_WRITE_MIN_FREQ_TABLE on LLC platforms

drm/xe: Only request PCODE_WRITE_MIN_FREQ_TABLE on LLC platforms

PCODE_WRITE_MIN_FREQ_TABLE is only applicable to platforms with an LLC.
Change the discrete GPU check to an LLC check instead; this take care of
skipping not only the discrete platforms, but also integrated platforms
like MTL that do not have an LLC.

Fixes MTL dmesg error:

  xe 0000:00:02.0: [drm] *ERROR* PCODE Mailbox failed: 1 Illegal Command

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230410183910.2696628-3-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>