drm/xe/guc: Add more KLV helper macros

In upcoming patches we will want to generate some of the KLV keys
from other macros. Add MAKE_GUC_KLV_{KEY|LEN} macros for that and
make sure they will correctly expand provided TAG parameter. Also
fix PREP_GUC_KLV_TAG to also work correctly within other macros.

Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240514190015.2172-2-michal.wajdeczko@intel.com