drm/xe/guc: Track pending-enable source in submission state

drm/xe/guc: Track pending-enable source in submission state

Add explicit tracking in the GuC submission state to record the source
of a pending enable (TDR vs. queue resume path vs. submission).
Disambiguating the origin lets the GuC submission state machine apply
the correct recovery/replay behavior.

This helps VF restore: when the device comes back, the state machine knows
whether the pending enable stems from timeout recovery, from a queue resume
sequence, or submission and can gate sequencing and fixups accordingly.

v4:
 - Clarify commit message (Tomasz)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: https://lore.kernel.org/r/20251008214532.3442967-4-matthew.brost@intel.com