tipc: Minor enhancements to name table display format

Eliminate printing of dashes after name table column headers
(to adhere more closely to the standard format used in tipc-config),
and simplify name table display logic using array lookups rather
than if-then-else logic.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>