drm/i915/dpll: drop unused but set variables bestn and bestm1

Prepare for re-enabling -Wunused-but-set-variable.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a85ccc8c0f451fcb997b4ac138dbeba2a653cebe.1685119007.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_dpll.c

@@ -1793,13 +1793,11 @@ static void chv_prepare_pll(const struct intel_crtc_state *crtc_state)
 	enum pipe pipe = crtc->pipe;
 	enum dpio_channel port = vlv_pipe_to_channel(pipe);
 	u32 loopfilter, tribuf_calcntr;
-	u32 bestn, bestm1, bestm2, bestp1, bestp2, bestm2_frac;
+	u32 bestm2, bestp1, bestp2, bestm2_frac;
 	u32 dpio_val;
 	int vco;
 
-	bestn = crtc_state->dpll.n;
 	bestm2_frac = crtc_state->dpll.m2 & 0x3fffff;
-	bestm1 = crtc_state->dpll.m1;
 	bestm2 = crtc_state->dpll.m2 >> 22;
 	bestp1 = crtc_state->dpll.p1;
 	bestp2 = crtc_state->dpll.p2;