vm_offset_t is unsigned, so compare of >= 0 is not needed.
vm_offset_t is unsigned, so compare of >= 0 is not needed.

Found with:	Coverity Prevent(tm)
CID:		2259

MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase