drm/amd/display: Fix dpp dto for disabled pipes

[Why]
When switching from 1 pipe to 4to1 mpc combine,
DppDtoClk aren't enabled for the disabled pipes
pior to programming the pipes. Upon optimizing
bandwidth, DppDto are enabled causing intermittent
underflow.

[How]
Update dppclk dto whenever pipe are flagged to
enable.

Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Reviewed-by: Hansen Dsouza <Hansen.Dsouza@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Duncan Ma <duncan.ma@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>