fbdev: sbuslib: use checked version of put_user()

I'm not sure why the code assumes that only the first put_user() needs
an access_ok() check.  I have made all the put_user() and get_user()
calls checked.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Peter Malone <peter.malone@gmail.com>,
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>