tipc: split variable assignments out of conditional expressions

Cleans up TIPC's source code to eliminate assigning values to variables
within conditional expressions, improving code readability and reducing
warnings from various code checker tools.

These changes are purely cosmetic and do not alter the operation of TIPC
in any way.

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>