net: dsa: remove unnecessary phy*.h includes

Including phy.h and phy_fixed.h into net/dsa.h causes phy*.h to be an
unnecessary dependency for quite a large amount of the kernel.  There's
very little which actually requires definitions from phy.h in net/dsa.h
- the include itself only wants the declaration of a couple of
structures and IFNAMSIZ.

Add linux/if.h for IFNAMSIZ, declarations for the structures, phy.h to
mv88e6xxx.h as it needs it for phy_interface_t, and remove both phy.h
and phy_fixed.h from net/dsa.h.

This patch reduces from around 800 files rebuilt to around 40 - even
with ccache, the time difference is noticable.
Tested-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/mv88e6xxx.h

@@ -15,6 +15,7 @@
 #include <linux/if_vlan.h>
 #include <linux/irq.h>
 #include <linux/gpio/consumer.h>
+#include <linux/phy.h>
 
 #ifndef UINT64_MAX
 #define UINT64_MAX		(u64)(~((u64)0))

include/net/dsa.h

@@ -11,17 +11,18 @@
 #ifndef __LINUX_NET_DSA_H
 #define __LINUX_NET_DSA_H
 
+#include <linux/if.h>
 #include <linux/if_ether.h>
 #include <linux/list.h>
 #include <linux/notifier.h>
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 #include <linux/of.h>
-#include <linux/phy.h>
-#include <linux/phy_fixed.h>
 #include <linux/ethtool.h>
 
 struct tc_action;
+struct phy_device;
+struct fixed_phy_status;
 
 enum dsa_tag_protocol {
 	DSA_TAG_PROTO_NONE = 0,