ima: pass HASH_ALGO__LAST as hash algo in ima_eventdigest_init()

Replace the '-1' value with HASH_ALGO__LAST in ima_eventdigest_init()
as the called function ima_eventdigest_init_common() expects an unsigned
char.

Fix commit:
  4d7aeee7 ima: define new template ima-ng and template fields d-ng and n-ng

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/ima/ima_template_lib.c

@@ -239,8 +239,8 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
 	cur_digest = hash.hdr.digest;
 	cur_digestsize = hash.hdr.length;
 out:
-	return ima_eventdigest_init_common(cur_digest, cur_digestsize, -1,
-					   field_data, true);
+	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
+					   HASH_ALGO__LAST, field_data, true);
 }
 
 /*