net/net.c: cosmetic: variable initializations

This removes the following checkpatch errors:
 - ERROR: do not initialise globals to 0 or NULL
 - ERROR: spaces required around that '=' (ctx:VxV)
 - ERROR: that open brace { should be on the previous line

Signed-off-by: Luca Ceresoli <luca.ceresoli@comelit.it>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Ben Warren <biggerbadderben@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>