input: linkdev: Register driver data once client devices are present

This fixes a bug where the driver data registered in the probe function
would be forgotten as soon as the probe function would return -EPROBE_DEFER.
input: linkdev: Send key release events when changing key map

When switching between the regular and the alternative key maps,
it is required that the input device does not report any of its keys
as pressed, otherwise the input handlers get confused. To avoid that,
we send a "key released" event for each of the keys we support, even
if the key isn't pressed in the first place.
fb: JZ4770: Allow hot-switching the "keep aspect ratio" param at runtime

This change makes sure that the IPU gets reconfigured as soon as the
keep_aspect_ratio parameter is written in sysfs.

Note that this commit has a side effect, the sysfs nodes moved in the
sysfs tree from /sys/module/jz4770-fb/parameters to
/sys/devices/platform/jz-lcd.0

For consistency, the allow_downscaling parameter moved as well to this
new directory.