ARM: PRIMA2: mv timer to timer-prima2 as we will add timer-marco

Marco timer has different timer IP with prima2, so rename the current timer
to timer-prima2 so that we can add timer-marco.

at the same time, if we don't find prima2 timer node in dt, don't panic the
system as we will make prima2 and marco use same kernel image.

Signed-off-by: Barry Song <Baohua.Song@csr.com>
diff --git a/arch/arm/mach-prima2/common.c b/arch/arm/mach-prima2/common.c
index ed3570e..8e6f668 100644
--- a/arch/arm/mach-prima2/common.c
+++ b/arch/arm/mach-prima2/common.c
@@ -40,7 +40,7 @@
 	/* Maintainer: Barry Song <baohua.song@csr.com> */
 	.map_io         = sirfsoc_map_lluart,
 	.init_irq	= sirfsoc_of_irq_init,
-	.init_time	= sirfsoc_timer_init,
+	.init_time	= sirfsoc_prima2_timer_init,
 	.dma_zone_size	= SZ_256M,
 	.init_machine	= sirfsoc_mach_init,
 	.init_late	= sirfsoc_init_late,