drm/amd/amdgpu/amdgpu_pll: Fix kernel-doc formatting, missing and extra params

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

 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:121: warning: Function parameter or member 'freq' not described in 'amdgpu_pll_compute'
 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:121: warning: Function parameter or member 'fb_div_p' not described in 'amdgpu_pll_compute'
 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:121: warning: Function parameter or member 'frac_fb_div_p' not described in 'amdgpu_pll_compute'
 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:121: warning: Function parameter or member 'ref_div_p' not described in 'amdgpu_pll_compute'
 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:121: warning: Function parameter or member 'post_div_p' not described in 'amdgpu_pll_compute'
 drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c:317: warning: Excess function parameter 'encoder' description in 'amdgpu_pll_get_shared_nondp_ppll'

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/amdgpu_pll.c

@@ -102,11 +102,12 @@ static void amdgpu_pll_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_
  * amdgpu_pll_compute - compute PLL paramaters
  *
  * @pll: information about the PLL
+ * @freq: requested frequency
  * @dot_clock_p: resulting pixel clock
- * fb_div_p: resulting feedback divider
- * frac_fb_div_p: fractional part of the feedback divider
- * ref_div_p: resulting reference divider
- * post_div_p: resulting reference divider
+ * @fb_div_p: resulting feedback divider
+ * @frac_fb_div_p: fractional part of the feedback divider
+ * @ref_div_p: resulting reference divider
+ * @post_div_p: resulting reference divider
  *
  * Try to calculate the PLL parameters to generate the given frequency:
  * dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
@@ -308,7 +309,6 @@ int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
  * amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
  *
  * @crtc: drm crtc
- * @encoder: drm encoder
  *
  * Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
  * be shared (i.e., same clock).