switch xattr_handler->set() to passing dentry and inode separately

preparation for similar switch in ->setxattr() (see the next commit for
rationale).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index eb3589e..0576eae 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -239,13 +239,13 @@
 }
 
 static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
-			      struct dentry *dentry, const char *name,
-			      const void *value, size_t size, int flags)
+			      struct dentry *dentry, struct inode *inode,
+			      const char *name, const void *value,
+			      size_t size, int flags)
 {
 	int retval;
 	struct posix_acl *acl;
 	struct v9fs_session_info *v9ses;
-	struct inode *inode = d_inode(dentry);
 
 	v9ses = v9fs_dentry2v9ses(dentry);
 	/*