Remove backward compatibility for dmraid without -P option (#788007)

The -P option was first added to dmraid-1.0.0.rc15 released 2006-09-17
[1].  dmraid-1.0.0.rc16 (a later release) was included in Debian 6 and
Ubunbu 12.04 LTS.  dmraid-1.0.0.rc13 was included in RedHat/CentOS 5
however the -P option was back ported into RedHat/CentOS 5.1.

All of these distributions are so old as to be no longer supported and
yet they provided the dmraid -P option.  Therefore backward
compatibility for dmraid without the -P option is no longer required.
So remove it.

[1] old dmraid source code releases
    http://people.redhat.com/heinzm/sw/dmraid/src/old/

Bug 788007 - Remove minor bits of legacy from DMRaid module