ARM: mach-shmobile: Use shared clock framework

Teach SH-Mobile ARM how to make use of the shared SH clock
framework. This commit is one atomic switch that dumps the
local hackery and instead links in the shared clock framework
code in drivers/sh. A few local functions are kept in clock.c.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>