arm64/ipipe: use virtual counter (cntvct) for tsc implementation.

arch/arm64/kernel/ipipe.c

@@ -50,6 +50,10 @@
 #include <asm/mmu_context.h>
 #include <asm/exception.h>
 
+#ifndef CONFIG_IPIPE_ARM_KUSER_TSC
+#include <asm/arch_timer.h>
+#endif
+
 static void __ipipe_do_IRQ(unsigned irq, void *cookie);
 
 #ifdef CONFIG_IPIPE_DEBUG_INTERNAL
@@ -591,6 +595,9 @@ void __ipipe_mach_get_tscinfo(struct __ipipe_tscinfo *info)
 {
 	*info = tsc_info;
 }
+unsigned long long __ipipe_mach_get_tsc(void) {
+	return arch_counter_get_cntvct();
+}
 #endif
 
 #if defined(CONFIG_IPIPE_DEBUG) && defined(CONFIG_DEBUG_LL)