ASoC: Sort DAPM power sequences while building lists

In the past the DAPM power sequencing was done by iterating over the list
of widgets once for each widget type and powering widgets of that type.
Instead of doing that do the sorting at the time we insert the widgets
into the lists of widgets to apply power changes to. This reduces the
amount of computation required for seqencing still further, though the
costs are generally dwarfed by the costs of the register writes
implementing them.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>