crypto: arm/crct10dif-ce - cleanup and optimizations

The x86, arm, and arm64 asm implementations of crct10dif are very
difficult to understand partly because many of the comments, labels, and
macros are named incorrectly: the lengths mentioned are usually off by a
factor of two from the actual code.  Many other things are unnecessarily
convoluted as well, e.g. there are many more fold constants than
actually needed and some aren't fully reduced.

This series therefore cleans up all these implementations to be much
more maintainable.  I also made some small optimizations where I saw
opportunities, resulting in slightly better performance.

This patch cleans up the arm version.

(Also moved the constants to .rodata as suggested by Ard Biesheuvel.)
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm/crypto/crct10dif-ce-glue.c

@@ -21,7 +21,7 @@
 
 #define CRC_T10DIF_PMULL_CHUNK_SIZE	16U
 
-asmlinkage u16 crc_t10dif_pmull(u16 init_crc, const u8 buf[], u32 len);
+asmlinkage u16 crc_t10dif_pmull(u16 init_crc, const u8 *buf, size_t len);
 
 static int crct10dif_init(struct shash_desc *desc)
 {