arc: Use the generic bitops headers

The generic bitops headers are required when calling logarithmic
functions, such as ilog2().

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

arch/arc/include/asm/bitops.h

@@ -16,4 +16,9 @@
 #define hweight16(x) generic_hweight16(x)
 #define hweight8(x) generic_hweight8(x)
 
+#include <asm-generic/bitops/fls.h>
+#include <asm-generic/bitops/__fls.h>
+#include <asm-generic/bitops/fls64.h>
+#include <asm-generic/bitops/__ffs.h>
+
 #endif /* __ASM_ARC_BITOPS_H */