Input: olpc_apsp - check FIFO status on open(), not probe()

Let's defer the FIFO status checking until open().

When we'll get a clk handle, this will allow us to defer clock enablement
until the device is actually used.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>