Fix outdated comments

Update the comment "../md32_common.h" to "crypto/md32_common.h".

CLA: trivial
Signed-off-by: Weiguo Li <liwg06@foxmail.com>
Reviewed-by: NPaul Dale <pauli@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/17670)

crypto/sha/sha1dgst.c

@@ -20,7 +20,7 @@
 #include <openssl/evp.h>
 #include <openssl/sha.h>
 
-/* The implementation is in ../md32_common.h */
+/* The implementation is in crypto/md32_common.h */
 
 #include "sha_local.h"
 #include "crypto/sha.h"

crypto/sha/sha512.c

@@ -25,7 +25,7 @@
  *   on [aligned] data in host byte order and one - on data in input
  *   stream byte order;
  * - share common byte-order neutral collector and padding function
- *   implementations, ../md32_common.h;
+ *   implementations, crypto/md32_common.h;
  *
  * Neither of the above applies to this SHA-512 implementations. Reasons
  * [in reverse order] are: