dpaa_eth: increment the RX dropped counter when needed

[ Upstream commit e4d1b37c17d000a3da9368a3e260fb9ea4927c25 ]

Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>