clocksource: arm_arch_timer: move arch_timer_needs_of_probing into DT init call

clocksource: arm_arch_timer: move arch_timer_needs_of_probing into DT init call

BugLink: http://bugs.launchpad.net/bugs/1688114
To cleanly split code paths specific to ACPI or DT at a higher level,
this patch removes arch_timer_init(), folding the relevant
parts of its logic into existing callers.

This pathes the way for further rework, and saves a few lines.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
[Mark: reword commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
(cherry picked from commit ca0e1b5214eee56a7fc4c7a5399323ab0bad73ef)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>