Revert "clockevents: Add a clkevt-of mechanism like clksrc-of"

After discussing it, this feature is dropped as it is not considered
adequate:

	https://patchwork.kernel.org/patch/9639317/



There is no user of this macro yet, so there is no impact on the drivers.

This reverts commit 376bc271.

Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>