drm/i915/request: drop kernel-doc

The documentation is closer to not being kernel-doc. Just drop the
kernel-doc /** indicators.

drivers/gpu/drm/i915/i915_request.h:176: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Request queue structure.
drivers/gpu/drm/i915/i915_request.h:477: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Returns true if seq1 is later than seq2.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/62a7a0f6e5b33e59ef4339304d01e7ef7ee04430.1683041799.git.jani.nikula@intel.com