drm/xe: move the kernel lrc from hwe to execlist port

drm/xe: move the kernel lrc from hwe to execlist port

The kernel lrc is used solely by the execlist infra.
Move it to the execlist port struct and initialize it only when
execlists are used.

v2: Rebase, improve error handling readability (Jonathan)

Signed-off-by: Ilia Levi <ilia.levi@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240826100655.1719060-1-ilia.levi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>