power: reset: account for const type of of_device_id.data

This driver creates a const structure that it stores in the data
field of an of_device_id array.

Add const to the declaration of the location that receives a value
from the data field to ensure that the compiler will continue to check
that the value is not modified and remove the const-dropping cast on
the access to the data field.

Done using Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>