amd-xgbe: Do not clear interrupt indicator

The interrupt value within the xgbe_ring_data structure is used as an
indicator of which Rx descriptor should have the INTE bit set to
generate an interrupt when that Rx descriptor is used.  This bit was
mistakenly cleared in the xgbe_unmap_rdata function, effectively
nullifying the ethtool rx-frames support.

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