Make netif_dbg use dynamic debugging whenever
CONFIG_DYNAMIC_DEBUG is enabled.

commit b558c96f
("dynamic_debug: make dynamic-debug supersede DEBUG ccflag")
missed updating the netif_dbg variant.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>