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>
diff --git a/board/voiceblue/voiceblue.c b/board/voiceblue/voiceblue.c
index c8dde36..59b3310 100644
--- a/board/voiceblue/voiceblue.c
+++ b/board/voiceblue/voiceblue.c
@@ -43,7 +43,7 @@
 	/* Take the Ethernet controller out of reset and wait
 	 * for the EEPROM load to complete. */
 	*((volatile unsigned short *) GPIO_DATA_OUTPUT_REG) |= 0x80;
-	udelay(10);	/* doesn't work before interrupt_init call */
+	udelay(10);	/* doesn't work before timer_init call */
 	*((volatile unsigned short *) GPIO_DATA_OUTPUT_REG) &= ~0x80;
 	udelay(500);