audio/forked-daapd: Remove substitions which are not related to variables

Remove %%PORTNAME%% and %%RC_NAME%% from:

• files/forked-daapd.in
• files/pkg-message.in

Reported by: mat (mentor)
Approved by: xxx (mentor)

Reported by: mat
Approved by: mat (mentor)
Differential Revision: https://reviews.freebsd.org/D6329