ARM: vexpress: Remove non-DT code

Now, with the CLCD DT support available, there is no
more reason to keep the non-DT support for V2P-CA9.

Removed, together with "some" supporting code. It was
necessary to make PLAT_VERSATILE_SCHED_CLOCK optional
and selected by the machines still interested in it.

Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>