smis.py: Check for duplicate volume name
smis.py: Check for duplicate volume name

If we fail to create a volume, lets check to see if we have
a volume with that name already.  If we do we will assume that
we failed because of duplicate volume name.  This is an O(N)
operation in the error path.

Signed-off-by: Tony Asleson <1ef2d381aa56d512126ddaacc29e68136e4fdf55@redhat.com>

joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,lazy404/libstoragemgmt,libstorage/libstoragemgmt,lazy404/libstoragemgmt,cathay4t/libstoragemgmt,tasleson/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,cathay4t/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,tasleson/libstoragemgmt,joehandzik/libstoragemgmt,jumitche/libstoragemgmt,lazy404/libstoragemgmt,cathay4t/libstoragemgmt,jumitche/libstoragemgmt,jumitche/libstoragemgmt,cathay4t/libstoragemgmt,libstorage/libstoragemgmt,libstorage/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,lazy404/libstoragemgmt,libstorage/libstoragemgmt,libstorage/libstoragemgmt