drm/i915: Update i915_reset parameter for kerneldoc

Since commit c033666a ("drm/i915: Store a i915 backpointer from
engine, and use it") i915_reset receives dev_priv, but the kerneldoc
was not updated.
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170112041817.1102-3-michel.thierry@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -1746,7 +1746,7 @@ static void enable_engines_irq(struct drm_i915_private *dev_priv)
 
 /**
  * i915_reset - reset chip after a hang
- * @dev: drm device to reset
+ * @dev_priv: device private to reset
  *
  * Reset the chip.  Useful if a hang is detected. Marks the device as wedged
  * on failure.