cxgb4: fix IRQ free race during driver unload

cxgb4: fix IRQ free race during driver unload

IRQs are requested during driver's ndo_open() and then later
freed up in disable_interrupts() during driver unload.
A race exists where driver can set the CXGB4_FULL_INIT_DONE
flag in ndo_open() after the disable_interrupts() in driver
unload path checks it, and hence misses calling free_irq().

Fix by unregistering netdevice first and sync with driver's
ndo_open(). This ensures disable_interrupts() checks the flag
correctly and frees up the IRQs properly.

Fixes: b37987e8db5f ("cxgb4: Disable interrupts and napi before unregistering netdev")
Signed-off-by: Shahjada Abul Husain <shahjada@chelsio.com>
Signed-off-by: Raju Rangoju <rajur@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>