drivers: net: xgene: fix extra IRQ issue

drivers: net: xgene: fix extra IRQ issue

BugLink: http://bugs.launchpad.net/bugs/1611399
For interrupt controller that doesn't support irq_disable and hardware
with level interrupt, an extra interrupt may be pending. This patch fixes
the issue by setting IRQ_DISABLE_UNLAZY flag for the interrupt line,
as suggested by,

'commit e9849777d0e2 ("genirq: Add flag to force mask in
		       disable_irq[_nosync]()")'

Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Tested-by: Toan Le <toanle@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit b5d7a06906a4875524f5c61c0b312828bf6737de linux-next)
Signed-off-by: Craig Magina <craig.magina@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>