insane.bbclass: fix the file-rdeps QA message for the new override syntax
Instead of replacing '_<pkg>', we should be replacing ':<pkg>'.
Otherwise, when we meet a 'file-rdeps' QA error, the error message would be
like below.
QA Issue: /usr/lib64/libatopology.so.2.0.0:libatopology contained in package libatopology ...
The ':libatopology' should not be in the error message.
Signed-off-by: Chen Qi <Qi.Chen@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>