crypto: arm/sha512 - Make sha512_arm_final static

Fix sparse warning:

arch/arm/crypto/sha512-glue.c:40:5: warning:
 symbol 'sha512_arm_final' was not declared. Should it be static?
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/arm/crypto/sha512-glue.c

@@ -37,7 +37,7 @@ int sha512_arm_update(struct shash_desc *desc, const u8 *data,
 		(sha512_block_fn *)sha512_block_data_order);
 }
 
-int sha512_arm_final(struct shash_desc *desc, u8 *out)
+static int sha512_arm_final(struct shash_desc *desc, u8 *out)
 {
 	sha512_base_do_finalize(desc,
 		(sha512_block_fn *)sha512_block_data_order);