UPSTREAM: lib/vdso: Allow the high resolution parts to be compiled out

If the architecture knows at compile time that there is no VDSO capable
clocksource supported it makes sense to optimize the guts of the high
resolution parts of the VDSO out at build time. Add a helper function to
check whether the VDSO should be high resolution capable and provide a stub
which can be overridden by an architecture.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200207124402.530143168@linutronix.de


(cherry picked from commit 1dff4156d1f63b525c54aea7f097a657cbbbf837)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 154668398
Change-Id: Ib024363345b8d75ffc78b3e5598a5720926f9358