[packaging] Drop boardname patch, use systemd/sysconfig in service file.

EnvironmentFile is defined in service file, and if
/etc/sysconfig/pulseaudio file is found, the contents of variable
$CONFIG are used in pulseaudio command line.
[packaging] Update pulseaudio.service file.
Merge pull request #13 from jusa/drop-boardname

[packaging] Drop boardname patch, use systemd/sysconfig in service file.