openrisc: Fix the bitmask for the unit present register

The bits were swapped, as per spec and processor implementation the
power management present bit is 9 and PIC bit is 8. This patch brings
the definitions into spec.

Signed-off-by: Sebastian Macke <sebastian@macke.de>
[shorne@gmail.com: Added commit body]
Signed-off-by: Stafford Horne <shorne@gmail.com>