[TIPC]: Cleanup of TIPC reference table code

This patch is a largely cosmetic cleanup of the TIPC reference
table code.
- The object reference field in each table entry is now single
  32-bit integer instead of a union of two 32-bit integers.
- Variable naming has been made more consistent.
- Error message output has been made more consistent.
- Useless #includes have been eliminated.

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