defconfig: am335x: gp_evm: enable ethernet driver model

enable ethernet driver model for am335x gp evm as cpsw supports
driver model

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

configs/am335x_gp_evm_defconfig

@@ -11,3 +11,4 @@ CONFIG_SYS_EXTRA_OPTIONS="NAND"
 CONFIG_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
 CONFIG_RSA=y
+CONFIG_DM_ETH=y