[TIPC]: Improve socket time conversions

This patch modifies TIPC's socket code to use standard kernel
routines to handle time conversions between jiffies and ms.
This ensures proper operation even when HZ isn't 1000.

Acknowledgements to Eric Sesterhenn <snakebyte@gmx.de> for
identifying this issue and proposing a solution.

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