arm: remove prototype for get_timer_masked

The interruption support had be removed for ARM architecture and
the function get_timer_masked() is no more used except in some
the timer.c files.

This patch clean each timer.c which implement this function and
remove the associated prototype in u-boot-arm.h

For timer.c, I don't verify if the weak version of get_timer
(in lib/time.c) can be used

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/arch/arm/mach-at91/arm920t/timer.c b/arch/arm/mach-at91/arm920t/timer.c
index 6a98d7c..6db541a 100644
--- a/arch/arm/mach-at91/arm920t/timer.c
+++ b/arch/arm/mach-at91/arm920t/timer.c
@@ -53,11 +53,6 @@
 /*
  * timer without interrupts
  */
-ulong get_timer(ulong base)
-{
-	return get_timer_masked() - base;
-}
-
 ulong get_timer_raw(void)
 {
 	at91_tc_t *tc = (at91_tc_t *) ATMEL_BASE_TC;
@@ -77,11 +72,16 @@
 	return gd->arch.tbl;
 }
 
-ulong get_timer_masked(void)
+static ulong get_timer_masked(void)
 {
 	return get_timer_raw()/TIMER_LOAD_VAL;
 }
 
+ulong get_timer(ulong base)
+{
+	return get_timer_masked() - base;
+}
+
 void __udelay(unsigned long usec)
 {
 	u32 tmo;