Revert "[BNX2]: Seems to not need net/tcp.h"

This reverts commit 963bd949.  The
driver _does_ need the networking header files;

	  CC [M]  drivers/net/bnx2.o
	drivers/net/bnx2.c: In function 'bnx2_start_xmit':
	drivers/net/bnx2.c:5177: warning: implicit declaration of function 'tcp_optlen'
	drivers/net/bnx2.c:5181: error: invalid application of 'sizeof' to incomplete type 'struct ipv6hdr'
	drivers/net/bnx2.c:5202: error: invalid application of 'sizeof' to incomplete type 'struct tcphdr'
	drivers/net/bnx2.c:5207: warning: implicit declaration of function 'tcp_hdr'
	drivers/net/bnx2.c:5207: error: invalid type argument of '->'
	make[2]: *** [drivers/net/bnx2.o] Error 1
	make[1]: *** [drivers/net] Error 2
	make: *** [drivers] Error 2

Cc: Ilpo Jävinen <ilpo.jarvinen@helsinki.fi>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>