drm/amd/display: fix dcn-specific clk_mgr init_clocks

[Why]
underflow seen on certain monitor setups caused by making dcnxx_init_hw
generic

[How]
by moving dcn20_init_hw into dcn10, we added a dcn-specific clk_mgr
init (dc->clk_mgr->funcs->init_clocks()). Thus, put old clk_mgr
memset in an else statement so both memsets don't get set
Signed-off-by: Martin Leung <martin.leung@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn10/rv1_clk_mgr.c

@@ -34,6 +34,11 @@
 #include "rv1_clk_mgr_vbios_smu.h"
 #include "rv1_clk_mgr_clk.h"
 
+void rv1_init_clocks(struct clk_mgr *clk_mgr)
+{
+	memset(&(clk_mgr->clks), 0, sizeof(struct dc_clocks));
+}
+
 static int rv1_determine_dppclk_threshold(struct clk_mgr_internal *clk_mgr, struct dc_clocks *new_clocks)
 {
 	bool request_dpp_div = new_clocks->dispclk_khz > new_clocks->dppclk_khz;
@@ -232,6 +237,7 @@ static void rv1_enable_pme_wa(struct clk_mgr *clk_mgr_base)
 }
 
 static struct clk_mgr_funcs rv1_clk_funcs = {
+	.init_clocks = rv1_init_clocks,
 	.get_dp_ref_clk_frequency = dce12_get_dp_ref_freq_khz,
 	.update_clocks = rv1_update_clocks,
 	.enable_pme_wa = rv1_enable_pme_wa,

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -1291,8 +1291,6 @@ static void dcn10_init_hw(struct dc *dc)
 	}
 
 	dc->hwss.enable_power_gating_plane(dc->hwseq, true);
-
-	memset(&dc->clk_mgr->clks, 0, sizeof(dc->clk_mgr->clks));
 }
 
 static void dcn10_reset_hw_ctx_wrap(