drm/amd/display: fix k1 k2 divider programming for phantom streams

drm/amd/display: fix k1 k2 divider programming for phantom streams

[ Upstream commit 3b214bb7185d8284d7d4c53e15127f69a375abf6 ]

[Why & How]
When k1 and k2 divider programming logic is executed for a phantom
stream, the corresponding master stream should be used for the
calculation. Fix the if condition to use the master stream for checking
signal type instead of the phantom stream.

Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 709671ffb15d ("drm/amd/display: Remove OTG DIV register write for Virtual signals.")
Signed-off-by: Sasha Levin <sashal@kernel.org>