net: Drop dm.h header file from phy.h

This header file should not be included in other header files. Remove it
and use other headers and C inclusions instead.

Signed-off-by: Simon Glass <sjg@chromium.org>

cmd/mdio.c

@@ -10,6 +10,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <dm.h>
 #include <miiphy.h>
 #include <phy.h>
 

cmd/mii.c

@@ -10,6 +10,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <dm.h>
 #include <miiphy.h>
 
 typedef struct _MII_field_desc_t {