drm/amd/display: Bug fix in dcn315_populate_dml_pipes_from_context

[Why]
When iterating over all pipes in the loop, the CRB allocation algorithm
may potentially skip some of the pipes. Previously, the current pipe
index didn't get updated in this case, causing incorrect outcome.

[How]
Increment the pipe index when skipping over a pipe in the loop.

Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Artem Grishin <artem.grishin@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>