ARM: call of_clk_init from default time_init handler

Most DT ARM machs require common clock providers initialized before timers.
Currently, arch/arm machs use .init_time to call of_clk_init right before
clocksource_of_init. This prevents to remove that callback and use the default
one instead.

This patch adds a call to of_clk_init() to the default .init_time callback
for COMMON_CLK enabled machs to allow to remove custom callbacks where applicable.
While at it, also reorder includes alphabetically.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>