drm/intel/bmg: Allow device ID usage with single-argument macros

drm/intel/bmg: Allow device ID usage with single-argument macros

When INTEL_BMG_G21_IDS were added as a subplatform, token concatenation
operator usage was omitted, making INTEL_BMG_IDS not usable with
single-argument macros.
Fix that by adding the missing operator.

Fixes: 78de8f876683 ("drm/xe: Handle Wa_22010954014 and Wa_14022085890 as device workarounds")
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patch.msgid.link/20251112132220.516975-25-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>