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>
diff --git a/configs/am335x_gp_evm_defconfig b/configs/am335x_gp_evm_defconfig
index 65c7b90..63b3fce 100644
--- a/configs/am335x_gp_evm_defconfig
+++ b/configs/am335x_gp_evm_defconfig
@@ -11,3 +11,4 @@
 CONFIG_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
 CONFIG_RSA=y
+CONFIG_DM_ETH=y