tipc: Enhancements to name table initialization

This patch enhances the initialization of TIPC's name table
by removing a pointless spinlock operation, and by using
kcalloc() to detect requests for an oversized name table.

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