Avoid integer wrap on remotePortMax in QEMU driver

Avoid integer wrap on remotePortMax in QEMU driver

The QEMU driver default max port is 65535, but it then increments
this by 1 to 65536. This maps to 0 in an unsigned short :-( This
was apparently done so that for() loops could use "< max" instead
of "<= max". Remove this insanity and just make the loop do the
right thing.