ktc: fix up initializer for local_tokens

The old initializer was incomplete (initializing only one of the four
fields in the struct), which prompted warnings from clang
(-Wmissing-field-initializers):
../../../openafs/src/auth/ktc.c:149:2: warning: missing field 'server'
      initializer [-Wmissing-field-initializers]

Since the variable is at file scope, it will be initialized to all
zeros anyway, and there is no need for an explicit initializer.

Change-Id: Ib7690759ec3403d1913852e30bb553ef8ac8f019
Reviewed-on: http://gerrit.openafs.org/10686
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>