desc: support descriptors 0x81, 0x86, 0xA0 & 0xA1 conditionally based on macro

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
build.sh: no longer any need to checkout new_descriptors branch

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>