habanalabs: add new return code to device fd open

In order to be more informative during device open, we are adding a
new return code -EAGAIN that indicates device is still going through
resource reclaiming and hence it cannot be used yet.

Signed-off-by: Ofir Bitton <obitton@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>