net: systemport: Fix missing Wake-on-LAN interrupt for SYSTEMPORT Lite

On SYSTEMPORT Lite, since we have the main interrupt source in the first
cell, the second cell is the Wake-on-LAN interrupt, yet the code was not
properly updated to fetch the second cell, and instead looked at the
third and non-existing cell for Wake-on-LAN.

Fixes: 44a4524c

 ("net: systemport: Add support for SYSTEMPORT Lite")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>