adb/fastboot: Support SuperSpeed USB devices

When enumerating USB 3.0 devices, a 6-byte SuperSpeed companion
descriptor follows each standard descriptor. The ADB and Fastboot
Linux clients currently fail to interpret these additional
descriptors and simply bail. Fix this by skipping over them.

Change-Id: I254dad8ed81e8de74a4fac36e8ce54b5da9715fe
Merge pull request #19 from CyanogenMod/cm-11.0

adb/fastboot: Support SuperSpeed USB devices