drm/i915/gt: Correct kerneldoc for intel_gt_mcr_wait_for_reg()

The kerneldoc function name was not updated when this function was
converted to a non-fw form.

Fixes: 192bb40f ("drm/i915/gt: Manage uncore->lock while waiting on MCR register")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221128233014.4000136-2-matthew.d.roper@intel.com