sh: Add SuperH Mobile MSTPCR bits to clock framework

Handle module stop clock bits in MSTPCRn through the clock framework.
The clocks are named after the bits in the data sheet. The association
between bit number and hardware block is processor specific.

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