[PATCH] vdpa/sfc: fix null pointer dereference

[Weiguo Li]

The macro sfc_vdpa_info(sva, ...) will invoke sva->logtype_main, 
It'll trigger a NULL dereference when sva is NULL.

This patch fix it.

BTW this patch is not superseded by another one:
 [v2] vdpa/sfc: fix null dereference
 (http://dpdk.org/patch/106720)

They looks alike in title, but deal with different files.

Please don't tag me as superseded again :)