x86: tsc: Identify Intel-specific code

try_msr_calibrate_tsc() is currently Intel-specific, and should not
execute on any other vendor's parts.

This keeps in sync with Linux kernel commit:
  ba82683: x86/tsc_msr: Identify Intel-specific code

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index ffbc709..4d01c9b 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -11,6 +11,7 @@
 #include <dm.h>
 #include <malloc.h>
 #include <timer.h>
+#include <asm/cpu.h>
 #include <asm/io.h>
 #include <asm/i8254.h>
 #include <asm/ibmpc.h>
@@ -86,6 +87,9 @@
 	unsigned long res;
 	int cpu_index;
 
+	if (gd->arch.x86_vendor != X86_VENDOR_INTEL)
+		return 0;
+
 	cpu_index = match_cpu(gd->arch.x86, gd->arch.x86_model);
 	if (cpu_index < 0)
 		return 0;