clk: add missing header

clk will use timer function, add timer.h include for it.

Signed-off-by: Pan Xiuli <xiuli.pan@linux.intel.com>

src/drivers/intel/baytrail/clk.c

@@ -30,6 +30,7 @@
  */
 
 #include <sof/drivers/clk.h>
+#include <sof/drivers/timer.h>
 #include <sof/clock.h>
 #include <sof/io.h>
 #include <sof/sof.h>

src/drivers/intel/cavs/clk.c

@@ -32,6 +32,7 @@
  */
 
 #include <sof/drivers/clk.h>
+#include <sof/drivers/timer.h>
 #include <sof/clock.h>
 #include <sof/io.h>
 #include <sof/sof.h>

src/drivers/intel/haswell/clk.c

@@ -29,6 +29,7 @@
  */
 
 #include <sof/drivers/clk.h>
+#include <sof/drivers/timer.h>
 #include <sof/clock.h>
 #include <sof/io.h>
 #include <sof/sof.h>