tipc: delete duplicate peerport/peernode helper functions

Prior to commit 23dd4cce387124ec3ea06ca30d17854ae4d9b772

    "tipc: Combine port structure with tipc_port structure"

there was a need for the two sets of helper functions.  But
now they are just duplicates.  Remove the globally visible
ones, and mark the remaining ones as inline.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>