drm/xe: Remove last fence dependency check from binds and execs

drm/xe: Remove last fence dependency check from binds and execs

Eliminate redundant last fence dependency checks in exec and bind jobs,
as they are now equivalent to xe_exec_queue_is_idle. Simplify the code
by removing this dead logic.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251031234050.3043507-7-matthew.brost@intel.com