drm/xe/guc: Fix size_t print format

drm/xe/guc: Fix size_t print format

Use %zx format to print size_t to remove the following warning when
building for i386:

>> drivers/gpu/drm/xe/xe_guc_ct.c:1727:43: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
    1727 |                         drm_printf(p, "[CTB].length: 0x%lx\n", snapshot->ctb_size);
         |                                                        ~~~     ^~~~~~~~~~~~~~~~~~
         |                                                        %zx

Cc: José Roberto de Souza <jose.souza@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501281627.H6nj184e-lkp@intel.com/
Fixes: cb1f868ca137 ("drm/xe: Make GUC binaries dump consistent with other binaries in devcoredump")
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250128154242.3371687-1-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>