[NET] socket: code style cleanup

Make socket.c conform to current style:
	* run through Lindent
	* get rid of unneeded casts
	* split assignment and comparsion where possible
Signed-off-by: NStephen Hemminger <shemminger@osdl.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>