drm/xe: Convert GuC CT print to snapshot capture and print.

The goal is to allow for a snapshot capture to be taken at the time
of the crash, while the print out can happen at a later time through
the exposed devcoredump virtual device.

v2: Handle memory allocation failures. (Matthew)
    Do not use GFP_ATOMIC on cases like debugfs prints. (Matthew)
v3: checkpatch fixes
v4: Do not use atomic in the g2h_worker_func (Matthew)

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>