dpaa2-eth: Simplify bool conversion

Fix the following coccicheck warnings:
./drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:1199:42-47: WARNING:
conversion to bool not needed here
./drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:1218:54-59: WARNING:
conversion to bool not needed here

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>