sound: Support sound conf file parsing existing rule

sound: Support sound conf file parsing existing rule

Previously, [Sound] section parsing was supported in sound.conf file.
However, as sound theme handling rule is changed to id-base, it was omitted.
If [Sound] section is used in sound.conf, default theme id will be set to 0.

Basically, it operates as follows.
1. When section [Sound] is found, sound-parser parses feedback pattern immediately.
    - This is origin sound.conf parsing style.
2. When section [SoundTheme] is found, sound-parser supports multiple sound theme usage.
    - This is new sound.conf parsing style as support multiple theme.
Thus, do not try to [Sound] and [SoundTheme] section at the same time in the sound.conf
Only one of the two styles may be selected and used.

Detailed description is added to common/data/sound.conf file.

Change-Id: I6f9274e91eb062898d45413f2b674663a7d4e30d
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>