r8169: don't use pci_irq_vector() in atomic context

Since referenced change pci_irq_vector() can't be used in atomic
context any longer. This conflicts with our usage of this function
in rtl8169_netpoll(). Therefore store the interrupt number in
struct rtl8169_private.

Fixes: 495c66ac

 ("genirq/msi: Convert to new functions")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/3cd24763-f307-78f5-76ed-a5fbf315fb28@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>