zephyr: imx: use zephyr utilities when enabled

Use the Zephyr sys/util.h when Zephyr RTOS is used.

While here, remove sof/lib/cpu.h which is not used.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>

src/platform/imx8/lib/clk.c

@@ -7,12 +7,15 @@
 
 #include <sof/common.h>
 #include <sof/lib/clk.h>
-#include <sof/lib/cpu.h>
 #include <sof/lib/memory.h>
 #include <sof/lib/notifier.h>
 #include <sof/sof.h>
 #include <sof/spinlock.h>
 
+#ifdef __ZEPHYR__
+#include <sys/util.h>
+#endif
+
 const struct freq_table platform_cpu_freq[] = {
 #ifdef CONFIG_IMX8
 	{ 666000000, 666000 },