I found a blog post that mentions a similar issue and MOS note that references the issue and workaround solution:
ASMLib: oracleasm createdisk command fails: Device '/dev/emcpowera1 is not a partition [Failed] (Doc ID 469163.1)
Now while this references EMC storage, the same issue and solution applies to other multipathing software and storage arrays such as Hitachi storage with HDLM in my case.
Instead of using the 'oracleasm createdisk' command I had to use an internal tool called asmtool that usually is called behind the scenes by Oracle tools.
# /usr/sbin/asmtool -C -l /dev/oracleasm -n VOL1 -s /dev/emcpowera1 -a force=yes