Fix: Set SOF_ALSA_TOOL to default value globally.

[gbarkadiusz]

Set SOF_ALSA_TOOL variable to a default value globally.
Justification:
After tinyalsa support was added (PR #1260), the use of SOF_ALSA_TOOL is now required for all tests before calling the aplay_opt or arecord_opt functions from lib.sh.

[golowanow]

Refactor the multiple-pipline.sh to use initialize_audio_params function.

Justification: After tinyalsa support was added (PR #1260), tests must set the $SOF_ALSA_TOOL variable before calling the aplay_opt or arecord_opt functions from lib.sh. The default value (alsa) for $SOF_ALSA_TOOL is set in the initialize_audio_params function.

Please don't mix 'fix' and 'refactor' purposes.

As a fix it is better to treat $SOF_ALSA_TOOL not defined as default 'alsa', or set $SOF_ALSA_TOOL 'alsa' default globally.
This way it should work for any test case not 'refactored' yet.

[gbarkadiusz]

Refactor the multiple-pipline.sh to use initialize_audio_params function.
Justification: After tinyalsa support was added (PR #1260), tests must set the $SOF_ALSA_TOOL variable before calling the aplay_opt or arecord_opt functions from lib.sh. The default value (alsa) for $SOF_ALSA_TOOL is set in the initialize_audio_params function.

Please don't mix 'fix' and 'refactor' purposes.

As a fix it is better to treat $SOF_ALSA_TOOL not defined as default 'alsa', or set $SOF_ALSA_TOOL 'alsa' default globally. This way it should work for any test case not 'refactored' yet.

WIP.

[golowanow]

Please make this PR as a fix only which works for all test case scripts and do 'refactoring' as a separate Pr (see also check-performance.sh)

[golowanow]

LGTM, but lets wait for test results