ARM: mxs: move timer driver into drivers/clocksource

Move mxs timer driver into drivers/clocksource as mxs_timer.c.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-mxs/Makefile

 # Common support
-obj-y := icoll.o ocotp.o system.o timer.o mm.o
+obj-y := icoll.o ocotp.o system.o mm.o
 
 obj-$(CONFIG_PM) += pm.o
 

drivers/clocksource/Makefile

@@ -16,6 +16,7 @@ obj-$(CONFIG_CLKSRC_NOMADIK_MTU)	+= nomadik-mtu.o
 obj-$(CONFIG_CLKSRC_DBX500_PRCMU)	+= clksrc-dbx500-prcmu.o
 obj-$(CONFIG_ARMADA_370_XP_TIMER)	+= time-armada-370-xp.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
+obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o
 obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
 obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o