drm/amd/display: Fix and reenable UPDATE_V3_FLOW_NEW_CONTEXT_MINIMAL

drm/amd/display: Fix and reenable UPDATE_V3_FLOW_NEW_CONTEXT_MINIMAL

[Why]
Reenable new split implementation, previously partially reverted due
to issues with ODM on high-bandwidth displays 4k144Hz, resulting
in a corrupted gray screen.

Minimal flows require two separate commits, with extra intermediate
commit to enable seamless transitions, each followed by a swap. Since
new design requires commit to be run in execute and swap in cleanup
stage, an attempt was made to reorder them from CSCS (Commit-Swap-Commit-Swap)
to CCSS (Commit-Commit-Swap-Swap). Not only is this not viable, but
was implemented incorrectly as CCS, one swap missing.

[How]
* Change UPDATE_V3_FLOW_NEW_CONTEXT_MINIMAL_NEW/CURRENT to execute
and cleanup one commit, then run UPDATE_V3_FLOW_NEW_CONTEXT_SEAMLESS,
which closely matches old implementation where minimal flows fall back
to seamless.
* Fix uninitialized variable error.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Dominik Kaszewski <dominik.kaszewski@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>