DSP Ops tester - Take 3

[ranj063]

This PR adds the API for enabling testing the DSP ops in the driver for testing the FW boot flow, PM flow etc. It introduces a new kernel config to enable the testing debugfs interface. When enabled, normal audio operations will be disabled.

For now the following ops are supported for testing:

1. boot_fw : To boot a firmware file pass from userspace by setting the fw_filename and fw_path debugfs files
2. dsp_power_state: To set the DSP state. CUrrent only D3 is supported with this op. SUpport for other states will be added soon.
3. fw_state: To check the current fw boot state