net: stmmac: Prevent divide-by-zero

When RX Coalesce settings are set to all zero (which is a valid setting)
we will currently get a divide-by-zero error. Fix it.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed