ASoC: wm_adsp: Separate concept of booted and running

Currently the wm_adsp driver has a flag that indicates the DSP is
"running", this flag is used to gate access to the hardware.  However this
flag is actually set in the firmware download thread after the firmware has
been downloaded, but this is before the core is actually started running,
so really it currently indicates that the core has been booted and is
perhaps running.

This patch clearly separates out the concepts of booted (firmware is
downloaded) and running (code is executing on the DSP) within the wm_adsp
driver.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>