ARM: OMAP4: cpuidle - Declare the states with the driver declaration

The cpuidle API allows to declare statically the states in the driver
structure. Let's use it.
We do no longer need the fill_cstate function called at runtime and
by the way adding more instructions at boot time.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>