GenWQE: Rework return code for flash-update ioctl

Instead of remaining bytes of a failing copy_to_user, the flash-update
ioctl is returning now -EFAULT. In addtion Dan discovered user triggerable
dev_errs(). Those I removed now from card_dev.c too. Some dev_infos()
were deleted and some others turned into dev_dbgs().
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>