ps3: fix rare issue that reenabling rx DMA fails

Fixed rare issue that 'lv1_net_start_rx_dma failed, status=-9" was shown
in dmesg.  This meant restarting rx DMA had been rejected by the hypervisor.
This issue would caused if the guest os requested starting DMA when
the hypervisor thought the DMA was in progress.
The state machine for DMA status of the hypervisor would be updated
by processing interrupt in the hypervisor.
Thus we should wait for the interrupt delivery before restarting
DMA.

Signed-off-by: Masakazu Mokuno <mokuno@sm.sony.co.jp>
Signed-off-by: Jeff Garzik <jeff@garzik.org>