drm/i915/utils: drop kernel-doc from __wait_for()

The parameters aren't documented, and the file isn't included in Sphinx
build anyway, so demote the kernel-doc to a regular comment.

drivers/gpu/drm/i915/i915_utils.h:284: warning: Function parameter or member 'OP' not described in '__wait_for'
drivers/gpu/drm/i915/i915_utils.h:284: warning: Function parameter or member 'COND' not described in '__wait_for'
drivers/gpu/drm/i915/i915_utils.h:284: warning: Function parameter or member 'US' not described in '__wait_for'
drivers/gpu/drm/i915/i915_utils.h:284: warning: Function parameter or member 'Wmin' not described in '__wait_for'
drivers/gpu/drm/i915/i915_utils.h:284: warning: Function parameter or member 'Wmax' not described in '__wait_for'

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e6e33a7f03c4a78739fa96e6ae74eb272ae147e7.1683041799.git.jani.nikula@intel.com