insane.bbclass: Fix incorrect getVar call

insane.bbclass: Fix incorrect getVar call

On a trace I was a bit puzzled why getVar was making 180 calls to len(d).
This is an expensive operation that should be very rarely called and
certainly not by getVar. In perl's do_package it was resulting in
~1.5 million function calls from those 180 cases.

Ultimately this typo was why. Lets fix it and save the CPU cyles.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>