tipc: Eliminate useless memset operations in Ethernet media support

Gets rid of two pointless operations that zero out the array used to
record information about TIPC's Ethernet bearers. There is no need to
initialize the array on start up since it is a global variable that is
already zero'd out, and there is no need to zero it out on exit because
the array is never referenced again.

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