staging: ccree: replace msleep with a completion

When the driver would try to queue commands to the HW FIFO but ran out of
slots it would use msleep as a delay until the FIFO would clear. This is
messy and not accurate.

Replace the msleep with a proper completion on the event of command
completion which should indicate at least one slot is free.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>