drm/amd/amdgpu/tonga_ih: Provide some missing descriptions for 'ih' and 'entry'

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/tonga_ih.c:193: warning: Function parameter or member 'ih' not described in 'tonga_ih_get_wptr'
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c:225: warning: Function parameter or member 'ih' not described in 'tonga_ih_decode_iv'
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c:225: warning: Function parameter or member 'entry' not described in 'tonga_ih_decode_iv'
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c:255: warning: Function parameter or member 'ih' not described in 'tonga_ih_set_rptr'

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/tonga_ih.c

@@ -181,6 +181,7 @@ static void tonga_ih_irq_disable(struct amdgpu_device *adev)
  * tonga_ih_get_wptr - get the IH ring buffer wptr
  *
  * @adev: amdgpu_device pointer
+ * @ih: IH ring buffer to fetch wptr
  *
  * Get the IH ring buffer wptr from either the register
  * or the writeback memory buffer (VI).  Also check for
@@ -215,6 +216,8 @@ static u32 tonga_ih_get_wptr(struct amdgpu_device *adev,
  * tonga_ih_decode_iv - decode an interrupt vector
  *
  * @adev: amdgpu_device pointer
+ * @ih: IH ring buffer to decode
+ * @entry: IV entry to place decoded information into
  *
  * Decodes the interrupt vector at the current rptr
  * position and also advance the position.
@@ -247,6 +250,7 @@ static void tonga_ih_decode_iv(struct amdgpu_device *adev,
  * tonga_ih_set_rptr - set the IH ring buffer rptr
  *
  * @adev: amdgpu_device pointer
+ * @ih: IH ring buffer to set rptr
  *
  * Set the IH ring buffer rptr.
  */