common: Drop net.h from common header

Move this header out of the common header. Network support is used in
quite a few places but it still does not warrant blanket inclusion.

Note that this net.h header itself has quite a lot in it. It could be
split into the driver-mode support, functions, structures, checksumming,
etc.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/atmel/at91rm9200ek/at91rm9200ek.c b/board/atmel/at91rm9200ek/at91rm9200ek.c
index e75d5b1..e4a6776 100644
--- a/board/atmel/at91rm9200ek/at91rm9200ek.c
+++ b/board/atmel/at91rm9200ek/at91rm9200ek.c
@@ -11,6 +11,7 @@
 
 #include <common.h>
 #include <init.h>
+#include <net.h>
 #include <netdev.h>
 #include <asm/mach-types.h>
 #include <asm/arch/hardware.h>
diff --git a/board/atmel/at91sam9n12ek/at91sam9n12ek.c b/board/atmel/at91sam9n12ek/at91sam9n12ek.c
index 90d3235..f16c137 100644
--- a/board/atmel/at91sam9n12ek/at91sam9n12ek.c
+++ b/board/atmel/at91sam9n12ek/at91sam9n12ek.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <init.h>
+#include <net.h>
 #include <vsprintf.h>
 #include <asm/io.h>
 #include <asm/arch/at91sam9x5_matrix.h>
diff --git a/board/atmel/common/mac-spi-nor.c b/board/atmel/common/mac-spi-nor.c
index 9634367..ced27b6 100644
--- a/board/atmel/common/mac-spi-nor.c
+++ b/board/atmel/common/mac-spi-nor.c
@@ -8,6 +8,7 @@
 #include <common.h>
 #include <dm.h>
 #include <env.h>
+#include <net.h>
 #include <linux/mtd/spi-nor.h>
 #include <netdev.h>
 
diff --git a/board/atmel/common/mac_eeprom.c b/board/atmel/common/mac_eeprom.c
index 050aa51..2205dd3 100644
--- a/board/atmel/common/mac_eeprom.c
+++ b/board/atmel/common/mac_eeprom.c
@@ -9,6 +9,7 @@
 #include <eeprom.h>
 #include <env.h>
 #include <i2c_eeprom.h>
+#include <net.h>
 #include <netdev.h>
 
 int at91_set_ethaddr(int offset)