staging: fsl-mc: don't use raw device io functions

As raw device io functions are not portable and don't handle byte-order
(triggering suspicion that endianness isn't handled well) switch to
using the standard api.
Since MC expects LE byte-order and the upper layers already take care
of that, we need to trick the device io api by doing a LE -> CPU
conversion just before calling it. This way, the CPU -> LE conversion
done in the api puts the data back in the right byte-order. Obviously,
for reads the extra step is mirrored: there's a CPU -> LE conversion
following the API call.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>