drm/amd/display: Add missing brackets in calculation

drm/amd/display: Add missing brackets in calculation

[ Upstream commit ea062fd28f922cb118bfb33229f405b81aff7781 ]

[Why]
Brackets missing in the calculation for MIN_DST_Y_NEXT_START

[How]
Add missing brackets for this calculation

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Daniel Miess <Daniel.Miess@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>