lib/raid6: add ARM-NEON accelerated syndrome calculation

Rebased/reworked a patch contributed by Rob Herring that uses
NEON intrinsics to perform the RAID-6 syndrome calculations.
It uses the existing unroll.awk code to generate several
unrolled versions of which the best performing one is selected
at boot time.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: hpa@linux.intel.com
diff --git a/include/linux/raid/pq.h b/include/linux/raid/pq.h
index 8dfaa2c..0f42469 100644
--- a/include/linux/raid/pq.h
+++ b/include/linux/raid/pq.h
@@ -114,6 +114,11 @@
 extern const struct raid6_recov_calls raid6_recov_ssse3;
 extern const struct raid6_recov_calls raid6_recov_avx2;
 
+extern const struct raid6_calls raid6_neonx1;
+extern const struct raid6_calls raid6_neonx2;
+extern const struct raid6_calls raid6_neonx4;
+extern const struct raid6_calls raid6_neonx8;
+
 /* Algorithm list */
 extern const struct raid6_calls * const raid6_algos[];
 extern const struct raid6_recov_calls *const raid6_recov_algos[];