If REG QUERY returns the string below (spaces included):
(Default) REG_SZ C:\Program Files\TeamSpeak 3 Client
... then you want the token after the second one separated by spaces (that is the default tokens separator), that is:
FOR /F "TOKENS=2*" %%a IN ('REG QUERY "HKLM\SOFTWARE\Wow6432Node\TeamSpeak 3 Client" /V "" 2^>NUL') DO SET TSLOC=%%b