ucm: Execute sequence of component devices

ucm: Execute sequence of component devices

A machine device's sequence can enable or disable a component device. So
when executing a machine device's sequence, the enable or disable sequence
of its component devices will also be excecuted.

Components don't define card device cdev in their sequences. So before
executing a component device sequence, UCM manager will
- store cdev defined by the sequence of its parent, the machine device;
- mark itself entering 'component domain'.

Then this cdev will be used to excute the sequence of the component
device.

When UCM manager completes executing the sequence of the component device,
it will leave 'compnent domain' and reset the saved cdev to NULL.

Signed-off-by: Mengdong Lin <mengdong.lin@linux.intel.com>
Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>