drivers: net: qe: deselect QE when DM_ETH is enabled

A compilation error appears when QE is compiled with DM_ETH
enabled:

drivers/qe/uec.c: In function 'init_phy':
drivers/qe/uec.c:425:28: error: dereferencing pointer to incomplete type 'struct eth_device'
  uec = (uec_private_t *)dev->priv;
                            ^~
drivers/qe/uec.c: In function 'uec_initialize':
drivers/qe/uec.c:1357:43: error: invalid application of 'sizeof' to incomplete type 'struct eth_device'
  dev = (struct eth_device *)malloc(sizeof(struct eth_device));
                                           ^~~~~~

The patch disables CONFIG_QE when CONFIG_DM_ETH is set.

Signed-off-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>