dsp: utils: slim down includes

The dsp/utils.h header itself only uses dsp/types.h and doesn't need the
entire dsp/dsp.h.

This also facilitates using the dsp/utils.h in builds that don't enable a
dsp backend at all which can be convenient for sensor drivers where the
q31_t dsp type is used.

Signed-off-by: Emil Dahl Juhl <emil@s16s.ai>

include/zephyr/dsp/utils.h

@@ -15,7 +15,7 @@
 
 #include <stdint.h>
 #include <zephyr/kernel.h>
-#include <zephyr/dsp/dsp.h>
+#include <zephyr/dsp/types.h>
 
 #ifdef __cplusplus
 extern "C" {