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/Kconfig b/drivers/timer/Kconfig
index 029af64..2b10d2b 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -23,4 +23,11 @@
 	  Select this to enable an emulated timer for sandbox. It gets
 	  time from host os.
 
+config X86_TSC_TIMER
+	bool "x86 Time-Stamp Counter (TSC) timer support"
+	depends on TIMER && X86
+	default y if X86
+	help
+	  Select this to enable Time-Stamp Counter (TSC) timer for x86.
+
 endmenu