common: Move clock functions into a new file

These three clock functions don't use driver model and should be migrated.
In the meantime, create a new file to hold them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/clk/mpc83xx_clk.c b/drivers/clk/mpc83xx_clk.c
index 69c6207..4183db2 100644
--- a/drivers/clk/mpc83xx_clk.c
+++ b/drivers/clk/mpc83xx_clk.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <clk-uclass.h>
+#include <clock_legacy.h>
 #include <dm.h>
 #include <vsprintf.h>
 #include <dm/lists.h>
diff --git a/drivers/net/ag7xxx.c b/drivers/net/ag7xxx.c
index 804d5c2..e3a7222 100644
--- a/drivers/net/ag7xxx.c
+++ b/drivers/net/ag7xxx.c
@@ -7,6 +7,7 @@
  */
 
 #include <common.h>
+#include <clock_legacy.h>
 #include <cpu_func.h>
 #include <dm.h>
 #include <errno.h>
diff --git a/drivers/serial/lpc32xx_hsuart.c b/drivers/serial/lpc32xx_hsuart.c
index 8b0fd25..7d31c6d 100644
--- a/drivers/serial/lpc32xx_hsuart.c
+++ b/drivers/serial/lpc32xx_hsuart.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <clock_legacy.h>
 #include <dm.h>
 #include <serial.h>
 #include <dm/platform_data/lpc32xx_hsuart.h>
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index 754b6e9..a92d2b1 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -4,6 +4,7 @@
  * modified to use CONFIG_SYS_ISA_MEM and new defines
  */
 
+#include <clock_legacy.h>
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
diff --git a/drivers/serial/serial_ar933x.c b/drivers/serial/serial_ar933x.c
index 5249c55..897ea5d 100644
--- a/drivers/serial/serial_ar933x.c
+++ b/drivers/serial/serial_ar933x.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <clock_legacy.h>
 #include <dm.h>
 #include <div64.h>
 #include <errno.h>
diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
index a1069f9..ef394b7 100644
--- a/drivers/serial/serial_ns16550.c
+++ b/drivers/serial/serial_ns16550.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <clock_legacy.h>
 #include <ns16550.h>
 #include <serial.h>
 #include <linux/compiler.h>
diff --git a/drivers/spi/ath79_spi.c b/drivers/spi/ath79_spi.c
index 0b8ebaa..f64a28c 100644
--- a/drivers/spi/ath79_spi.c
+++ b/drivers/spi/ath79_spi.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <clock_legacy.h>
 #include <spi.h>
 #include <dm.h>
 #include <div64.h>