drm/xe: Move lrc snapshot capturing to xe_lrc.c

This allows the dumping of HWSP and HW Context without exporting more
functions.

Changes since v1:
- GFP_KERNEL -> GFP_NOWAIT. (Souza)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240227131248.92910-1-maarten.lankhorst@linux.intel.com