sh: setup timers in late_time_init()

This patch moves the SuperH timer setup code from time_init()
to late_time_init(). Good things about this change:
 - interrupts: they are enabled at late_time_init()
 - mm: regular kmalloc() can be used at late_time_init()

Together with moving to late_time_init() this patch changes
the sh_cmt driver to always allocate with kmalloc(). This
simplifies the code a bit and also fixes section mismatches.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>