Fix incorrect handling of 'ANY' slot type

Resulted in segfault in vtllibrary

This 'read element status' would trigger the segfault.
sg_raw -r 1k /dev/sg12 b8 10 00 01 00 39 01 00 0d 30 00 00 00 00 00 00

Reference:
http://mhvtl-linux-virtual-tape-library-community-forums.966029.n3.nabble.com/Kernel-Problems-since-1-Day-td4025337.html

Reported-by: Holliefant on mhvtl-linux-virtual-tape-library-community-forums
Signed-off-by: Mark Harvey <markh794@gmail.com>