sh: clkfwk: remove bogus set_bus_parent() from SH7709.

This fixes up broken clock re-parenting undertaken by the SH7709 clock
framework code, which is currently in conflict with the legacy CPG
framework. With this change in place, the legacy CPG ancestry is used,
and we manage to avoid contending on the clock_list_sem mutex, which is
already held under the legacy registration path, resulting in livelock.

In order for SH7709 to fully support the varying clock modes, it needs to
implement a more complete clock framework. After this change it is in
sync with legacy CPG mode, which ends up being the default configuration
for this CPU anyways.

Signed-off-by: Rafael Ignacio Zurita <rizurita@yahoo.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>