ARM: rationalize versatile family Kconfig/Makefile

Move leds and sched_clock build conditionals out of the Makefile into
the Kconfig file.  Move selection of HAVE_SCHED_CLOCK into the
platform Kconfig rather than duplicating it three times in the main
architecture Kconfig.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>