net: macb: Add default usrio config to default gem config

There is no usrio config defined for default gem config leading to
a kernel panic devices that don't define a data. This issue can be
reprdouced with microchip polar fire soc where compatible string
is defined as "cdns,macb".

Fixes: edac638 ("net: macb: add userio bits as platform configuration")
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>

drivers/net/ethernet/cadence/macb_main.c

@@ -4590,6 +4590,7 @@ static const struct macb_config default_gem_config = {
 	.dma_burst_length = 16,
 	.clk_init = macb_clk_init,
 	.init = macb_init,
+	.usrio = &macb_default_usrio,
 	.jumbo_max_len = 10240,
 };