lib/vdso: Update coarse timekeeper unconditionally

The low resolution parts of the VDSO, i.e.:

  clock_gettime(CLOCK_*_COARSE), clock_getres(), time()

can be used even if there is no VDSO capable clocksource.

But if an architecture opts out of the VDSO data update then this
information becomes stale. This affects ARM when there is no architected
timer available. The lack of update causes userspace to use stale data
forever.

Make the update of the low resolution parts unconditional and only skip
the update of the high resolution parts if the architecture requests it.

Fixes: 44f57d78 ("timekeeping: Provide a generic update_vsyscall() implementation")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200114185946.765577901@linutronix.de