net: cleanup unused macros in net directory

Clean up some unused macros in net/*.
1. be left for code change. e.g. PGV_FROM_VMALLOC, PGV_FROM_VMALLOC, KMEM_SAFETYZONE.
2. never be used since introduced to kernel.
   e.g. P9_RDMA_MAX_SGE, UTIL_CTRL_PKT_SIZE.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/caif/cfveil.c b/net/caif/cfveil.c
index 3b425b1..c3b1dec 100644
--- a/net/caif/cfveil.c
+++ b/net/caif/cfveil.c
@@ -17,7 +17,7 @@
 #define VEI_FLOW_OFF 0x81
 #define VEI_FLOW_ON  0x80
 #define VEI_SET_PIN  0x82
-#define VEI_CTRL_PKT_SIZE 1
+
 #define container_obj(layr) container_of(layr, struct cfsrvl, layer)
 
 static int cfvei_receive(struct cflayer *layr, struct cfpkt *pkt);