crypto: sun4i-ss - mark sun4i_hash() static

We get 1 warning when building kernel with W=1:
drivers/crypto/sunxi-ss/sun4i-ss-hash.c:168:5: warning: no previous prototype for 'sun4i_hash' [-Wmissing-prototypes]

In fact, this function is only used in the file in which it is
declared and don't need a declaration, but can be made static.
So this patch marks it 'static'.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/sunxi-ss/sun4i-ss-hash.c

@@ -165,7 +165,7 @@ int sun4i_hash_import_sha1(struct ahash_request *areq, const void *in)
  * write remaining data in op->buf
  * final state op->len=56
  */
-int sun4i_hash(struct ahash_request *areq)
+static int sun4i_hash(struct ahash_request *areq)
 {
 	u32 v, ivmode = 0;
 	unsigned int i = 0;