common: Move get_tbclk() to time.h

This function related to timer and most of the timer functions are in
time.h, so move this function there.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-orion5x/timer.c b/arch/arm/mach-orion5x/timer.c
index 9da9783..077eb63 100644
--- a/arch/arm/mach-orion5x/timer.c
+++ b/arch/arm/mach-orion5x/timer.c
@@ -165,7 +165,7 @@
  * This function is derived from PowerPC code (timebase clock frequency).
  * On ARM it returns the number of timer ticks per second.
  */
-ulong get_tbclk (void)
+ulong get_tbclk(void)
 {
 	return (ulong)CONFIG_SYS_HZ;
 }