sh: Merge sh7343 and sh7722 clock code

This code makes sh7343 share the sh7722 clock code. Instead of just using
the good and very old sh7343 clock implmentation, switch to the new MSTPCR
enabled clock code. SIU clocks are disabled on sh7343 for now.

With this change all SuperH Mobile devices now use the same clock code.

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