ARM: mach-shmobile: cpuidle single/global and last_state fixes

The following commits break cpuidle on SH-Mobile ARM:

46bcfad7 cpuidle: Single/Global registration of idle states
e978aa7d cpuidle: Move dev->last_residency update to driver enter routine; remove dev->last_state

This patch remedies these issues by up-porting the SH-Mobile
code to fit with the above introduced framework changes.

It is worth noting that the new code becomes significantly cleaner,
so these framework changes are very welcome. At the same time this
breakage could probably have been avoided by grepping for "last_state"
and "cpuidle_register_driver".

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>