physmem: keep only one physmem_main

We don't need per vlib_main physmem_main, so keep it separatelly instead
of trying to keep them in sync.

Change-Id: I0fbeecf4d9672d31af7a43c640a7d8f05dd6e46f
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/unix/main.c b/src/vlib/unix/main.c
index 7e868f9..786addf 100644
--- a/src/vlib/unix/main.c
+++ b/src/vlib/unix/main.c
@@ -61,6 +61,7 @@
 
 unix_main_t unix_main;
 clib_file_main_t file_main;
+vlib_physmem_main_t physmem_main;
 
 static clib_error_t *
 unix_main_init (vlib_main_t * vm)