configs: k2l_evm: add random eth address support

There is only one ethernet mac address in e-fuse, but there are
multiple slaves in keystone net, so enable random mac address
support.
Signed-off-by: NMugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: NTom Rini <trini@konsulko.com>

configs/k2l_evm_defconfig

@@ -37,3 +37,5 @@ CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_DWC3=y
+CONFIG_LIB_RAND=y
+CONFIG_NET_RANDOM_ETHADDR=y