quota: Silence warning about PRJQUOTA not being handled in need_print_warning()

PRJQUOTA value of quota type should never reach need_print_warning() since XFS
(which is the only fs which uses that type) doesn't use generic functions
calling this function. Anyway, add PRJQUOTA case to the switch to make gcc
happy.
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -1160,6 +1160,8 @@ static int need_print_warning(struct dquot_warn *warn)
 			return uid_eq(current_fsuid(), warn->w_dq_id.uid);
 		case GRPQUOTA:
 			return in_group_p(warn->w_dq_id.gid);
+		case PRJQUOTA:	/* Never taken... Just make gcc happy */
+			return 0;
 	}
 	return 0;
 }