drm/xe: Drop undesired prefix from the platform name

drm/xe: Drop undesired prefix from the platform name

We don't have to use exact names of the enumerators as the
potentially user-facing platform names. When constructing
platform descriptor fields, use the unique platform tag and
add the XE_ prefix only to the generated enum field.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240521142257.756-3-michal.wajdeczko@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>