LoongArch/crypto: Clean up useless assignment operations

The LoongArch CRC32 hw acceleration is based on arch/mips/crypto/
crc32-mips.c. While the MIPS code supports both MIPS32 and MIPS64,
but LoongArch32 lacks the CRC instruction. As a result, the line
"len -= sizeof(u32)" is unnecessary.

Removing it can make context code style more unified and improve
code readability.

Cc: stable@vger.kernel.org
Reviewed-by: WANG Xuerui <git@xen0n.name>
Suggested-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Yuli Wang <wangyuli@uniontech.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

crypto: loongarch/crc32 - remove redundant setting of alignmask to 0

This unnecessary explicit setting of cra_alignmask to 0 shows up when
grepping for shash algorithms that set an alignmask. Remove it. No
change in behavior.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

LoongArch: crypto: Add crc32 and crc32c hw acceleration

With a blatant copy of some MIPS bits we introduce the crc32 and crc32c
hw accelerated module to LoongArch.

LoongArch has provided these instructions to calculate crc32 and crc32c:
* crc.w.b.w crcc.w.b.w
* crc.w.h.w crcc.w.h.w
* crc.w.w.w crcc.w.w.w
* crc.w.d.w crcc.w.d.w

So we can make use of these instructions to improve the performance of
calculation for crc32(c) checksums.

As can be seen from the following test results, crc32(c) instructions
can improve the performance by 58%.

Software implemention Hardware acceleration
Buffer size time cost (seconds) time cost (seconds) Accel.
100 KB 0.000845 0.000534 59.1%
1 MB 0.007758 0.004836 59.4%
10 MB 0.076593 0.047682 59.4%
100 MB 0.756734 0.479126 58.5%
1000 MB 7.563841 4.778266 58.5%

Signed-off-by: Min Zhou <zhoumin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>