drm/amd/display: fix wrong index used in dccg32_set_dpstreamclk

[Why & How]
When merging commit 9af611f
("drm/amd/display: Fix DCN32 DPSTREAMCLK_CNTL programming"),
index change was not picked up.

Cc: stable@vger.kernel.org
Cc: Mario Limonciello <mario.limonciello@amd.com>
Fixes: 9af611f ("drm/amd/display: Fix DCN32 DPSTREAMCLK_CNTL programming")
Reviewed-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Hersen Wu

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c

@@ -271,8 +271,7 @@ static void dccg32_set_dpstreamclk(
 	dccg32_set_dtbclk_p_src(dccg, src, otg_inst);
 
 	/* enabled to select one of the DTBCLKs for pipe */
-	switch (otg_inst)
-	{
+	switch (dp_hpo_inst) {
 	case 0:
 		REG_UPDATE_2(DPSTREAMCLK_CNTL,
 			     DPSTREAMCLK0_EN,