upspin: remove unused getBytes and getNBytes functions
upspin: remove unused getBytes and getNBytes functions

Change-Id: Ia3a0bb68693d7a8a81b0675c9571fc4f0387d19a
Reviewed-on: https://upspin-review.googlesource.com/18600
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

upspin/upspin,upspin/upspin