zero i_uid/i_gid on inode allocation

... and don't bother in callers.  Don't bother with zeroing i_blocks,
while we are at it - it's already been zeroed.

i_mode is not worth the effort; it has no common default value.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/openpromfs/inode.c

@@ -256,9 +256,6 @@ found:
 		break;
 	}
 
-	inode->i_gid = 0;
-	inode->i_uid = 0;
-
 	d_add(dentry, inode);
 	return NULL;
 }