amd-xgbe: Free channel/ring structures later

The channel structure is freed before freeing the per channel
interrupts resulting in a kernel oops. Move the call to free
the channel structure to after the freeing of the per channel
interrupts.

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