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/include/configs/ixdpg425.h b/include/configs/ixdpg425.h
index 75707e5..0c09234 100644
--- a/include/configs/ixdpg425.h
+++ b/include/configs/ixdpg425.h
@@ -55,6 +55,7 @@
  */
 #undef CONFIG_USE_IRQ			/* we don't need IRQ/FIQ stuff	*/
 #define CONFIG_USE_IRQ          1	/* we need IRQ stuff for timer	*/
+#define CONFIG_TIMER_IRQ
 
 #define CONFIG_BOOTCOUNT_LIMIT		/* support for bootcount limit	*/
 #define CONFIG_SYS_BOOTCOUNT_ADDR	0x60003000 /* inside qmrg sram		*/