freezer: define try_to_freeze_nowarn if CONFIG_FREEZER=n

Fixes build since:
  0e432e6 HACK: ARM: disable sleeping while atomic warning in do_signal

Change-Id: I451217171c6beb55ab4d190e1248ddbc9a2d9516
Signed-off-by: Ben Jones <ben.jones@imgtec.com>
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index b4bd522..ef22a8c 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -315,6 +315,7 @@
 static inline void thaw_processes(void) {}
 static inline void thaw_kernel_threads(void) {}
 
+static inline bool try_to_freeze_nowarn(void) { return false; }
 static inline bool try_to_freeze(void) { return false; }
 
 static inline void freezer_do_not_count(void) {}