um: get rid of pointless include "..." where include <...> will do

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 1fe7313..9c88da0 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -1,7 +1,7 @@
 #ifndef __UM_FS_HOSTFS
 #define __UM_FS_HOSTFS
 
-#include "os.h"
+#include <os.h>
 
 /*
  * These are exactly the same definitions as in fs.h, but the names are