igb: Fix for improper exit in igb_get_i2c_client

This patch fixes an issue where we check for irq's disabled then exit after
explicitly disabling them with spin_lock_irqsave.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <arron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>