ARM: tegra: move timer.c to drivers/clocksource/

Move arch/arm/mach-tegra/timer.c to drivers/clocksource/tegra20_timer.c
so that the code is co-located with other clocksource drivers, and to
reduce the size of the mach-tegra directory.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index a33f792..b5cc507 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -17,5 +17,6 @@
 obj-$(CONFIG_ARMADA_370_XP_TIMER)	+= time-armada-370-xp.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
 obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o
+obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
 
 obj-$(CONFIG_CLKSRC_ARM_GENERIC)	+= arm_generic.o