util_macros.h: add missing inclusion

The header is the direct user of definitions from the math.h, include it.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/util_macros.h

···
 #ifndef _LINUX_HELPER_MACROS_H_
 #define _LINUX_HELPER_MACROS_H_
 
+#include <linux/math.h>
+
 #define __find_closest(x, a, as, op)					\
 ({									\
 	typeof(as) __fc_i, __fc_as = (as) - 1;				\