kernel: add calibration_delay_done()

Add calibration_delay_done() call and dummy implementation. This allows
architectures to stop accepting registrations for new timer based delay
functions.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

init/calibrate.c

@@ -262,6 +262,15 @@ unsigned long __attribute__((weak)) calibrate_delay_is_known(void)
 	return 0;
 }
 
+/*
+ * Indicate the cpu delay calibration is done. This can be used by
+ * architectures to stop accepting delay timer registrations after this point.
+ */
+
+void __attribute__((weak)) calibration_delay_done(void)
+{
+}
+
 void calibrate_delay(void)
 {
 	unsigned long lpj;
@@ -301,4 +310,6 @@ void calibrate_delay(void)
 
 	loops_per_jiffy = lpj;
 	printed = true;
+
+	calibration_delay_done();
 }