KVM: arm64: selftests: Split arch_timer test code

Split the arch-neutral test code out of aarch64/arch_timer.c
and put them into a common arch_timer.c. This is a preparation
to share timer test codes in riscv.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Haibo Xu <haibo1.xu@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

tools/testing/selftests/kvm/include/test_util.h

@@ -20,6 +20,8 @@
 #include <sys/mman.h>
 #include "kselftest.h"
 
+#define msecs_to_usecs(msec)    ((msec) * 1000ULL)
+
 static inline int _no_printf(const char *format, ...) { return 0; }
 
 #ifdef DEBUG