ASoC: SOF: Intel: bdw: Use generic function for fw ready / mem windows creation

ASoC: SOF: Intel: bdw: Use generic function for fw ready / mem windows creation

bdw_get_windows / bdw_fw_ready is identical with the generic
implementation introduced in a previous patch.

So remove bdw_get_windows / bdw_fw_ready and use the generic
sof_get_windows version.

Do not forget to implement get_mailbox_offset/get_window_offset
so that we export the correct mailbox/memory window offset to
the outside world.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190807150203.26359-6-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>