key/inprocess: remove unnecessary lock operation
key/inprocess: remove unnecessary lock operation

Change-Id: Ib0e7a95dddb0a57f6ae6d36ac93447ec216bca82
Reviewed-on: https://upspin-review.googlesource.com/4209
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@google.com>

upspin/upspin,upspin/upspin