x86: tsc: Move tsc_timer.c to drivers/timer

To group all dm timer drivers together, move tsc timer to
drivers/timer directory.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index 300946e..fe954eca 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -7,3 +7,4 @@
 obj-$(CONFIG_TIMER)		+= timer-uclass.o
 obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
 obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
+obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o