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>

arch/loongarch/crypto/crc32-loongarch.c

@@ -44,7 +44,6 @@ static u32 crc32_loongarch_hw(u32 crc_, const u8 *p, unsigned int len)
 
 		CRC32(crc, value, w);
 		p += sizeof(u32);
-		len -= sizeof(u32);
 	}
 
 	if (len & sizeof(u16)) {
@@ -80,7 +79,6 @@ static u32 crc32c_loongarch_hw(u32 crc_, const u8 *p, unsigned int len)
 
 		CRC32C(crc, value, w);
 		p += sizeof(u32);
-		len -= sizeof(u32);
 	}
 
 	if (len & sizeof(u16)) {