selftests/powerpc: Include asm/cputable.h from utils.h

utils.h provides have_hwcap() and have_hwcap2() which check for a
feature bit. Those bits are defined in asm/cputable.h, so include it
in utils.h so users of utils.h don't have to do it manually.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015727.1977134-4-mpe@ellerman.id.au

tools/testing/selftests/powerpc/stringloops/memcmp.c

@@ -4,7 +4,7 @@
 #include <string.h>
 #include <sys/mman.h>
 #include <time.h>
-#include <asm/cputable.h>
+
 #include "utils.h"
 
 #define SIZE 256