amd-xgbe: Interrupt summary bits are h/w version dependent

There is a difference in the bit position of the normal interrupt summary
enable (NIE) and abnormal interrupt summary enable (AIE) between revisions
of the hardware.  For older revisions the NIE and AIE bits are positions
16 and 15 respectively.  For newer revisions the NIE and AIE bits are
positions 15 and 14.  The effect in changing the bit position is that
newer hardware won't receive AIE interrupts in the current version of the
driver.  Specifically, the driver uses this interrupt to collect
statistics on when a receive buffer unavailable event occurs and to
restart the driver/device when a fatal bus error occurs.

Update the driver to set the interrupt enable bit based on the reported
version of the hardware.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>