drm/i915: Introduce intel_gt_mcr_lock_sanitize()

Implement intel_gt_mcr_lock_sanitize() to provide a mechanism
for cleaning the steer semaphore when absolutely necessary.

v2: remove unnecessary lock(Andi, Matt)
    improve the kernel doc(Matt)
    s/intel_gt_mcr_lock_clear/intel_gt_mcr_lock_sanitize

Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230928130015.6758-1-nirmoy.das@intel.com