arm: timer and interrupt init rework

actually the timer init use the interrupt_init as init callback
which make the interrupt and timer implementation difficult to follow

so now rename it as int timer_init(void) and use interrupt_init for interrupt

btw also remane the corresponding file to the functionnality implemented

as ixp arch implement two timer - one based on interrupt - so all the timer
related code is moved to timer.c

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

cpu/s3c44b0/Makefile

@@ -26,7 +26,10 @@ include $(TOPDIR)/config.mk
 LIB	= $(obj)lib$(CPU).a
 
 START	= start.o
-COBJS	= cache.o cpu.o interrupts.o
+
+COBJS	+= cache.o
+COBJS	+= cpu.o
+COBJS	+= timer.o
 
 SRCS	:= $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))

cpu/s3c44b0/timer.c

@@ -40,7 +40,7 @@
 static ulong timestamp;
 static ulong lastdec;
 
-int interrupt_init (void)
+int timer_init (void)
 {
 	TCFG0 = 0x000000E9;
 	TCFG1 = 0x00000004;