PXA2xx

Patch from Nicolas Pitre

Let's make sure OSCR doesn't end up to be restored with a value
past OSMR0 otherwise the system timer won't start ticking until
OSCR wraps around (aprox 17 min.

Also set OSCR _after_ OIER is restored to avoid matching when
corresponding match interrupt is masked out.

Signed-off-by: Nicolas Pitre