Set SDEV_UMASS on all umass devices, even when they use ATAPI or

Set SDEV_UMASS on all umass devices, even when they use ATAPI or
UFI command sets. Probe all the LUNs a device reports instead of
assuming ATAPI and UFI devices always have 1 LUN.

Motivated by the device David Vasek reported as claiming to be
ATAPI but wanting to use >1 LUN. Committing quickly to smoke out
the inevitable device that works in the exact opposite way. All
hail USB.

ok kettenis@