Addition ioctl support for Intel G33/Q33,Q35 chipsets in i915 driver

1. Summary
  DRM (direct rendering management) kernel module and i915 driver were introduced to Solaris in 
  PSARC 2004/801.  The ioctl's exported by this driver include both hardware independent
  and hardware dependent ones.  Recently, Intel released their G33/Q33,Q35 chipsets
  with embedded graphics that required a new Intel specific ioctl in the driver.
  This case documents this new ioctl.

2. Discussion
   The third argument of the prefixioctl (ioctl(9E)) should point to the structure
   below.  The usage of the first argument 'dev' and the second argument 'cmd' follow
   the same pattern of other ioctl's.

   struct drm_i915_hws_addr {
     uint64_t addr;       /* the offset of hardware status page */
   };

3. Interface Table
   -----------------------------------------------------------------------------------------
   | Interface exported       | Classifications   | Comments                               |
   -----------------------------------------------------------------------------------------
   | DRM_IOCTL_I915_HWS_ADDR  | External          | Set the offset of hardware status page |
   -----------------------------------------------------------------------------------------

4. References:
    CR6604682 DRM support for Intel G/Q 3 series

5. Documentation Change
     The i915(7D) man page shall include additional chipset
     support information by the i915 driver with this change.