ibmvnic: Fix assignment of RX/TX IRQ's

The driver currently creates RX/TX queues during device probe, but
assigns IRQ's to them during device open. On reset, however,
IRQ's are assigned when resetting the queues. If there is a reset
while the device is closed and the device is later opened, the driver will
request IRQ's twice, causing the open to fail. This patch assigns
the IRQ's in the ibmvnic_init function after the queues are reset or
initialized, ensuring IRQ's are only requested once.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>