Use different naming for the actual DPM size and for the DPM address range reserved by the cifX driver

When displaying system information or system channel information (selections "Generic Information" or "Info Block"), cifX Test shows the entry "DPM Total Size". (For cifX 50 cards the typical value is 32768.)

When selecting a device in the "Channel Selection" dialog, cifX Test shows the entry "DPM Size". (For cifX 50 cards the typical value is 65536.)

The latter entry should be renamed to "DPM Reserved Address Space" or to "DPM Aperture Size" to denote that this is the memory address range reserved by the cifX driver for DPM access by the host application.