net: tsec: Mark tsec_get_interface as __maybe_unused

Non DM builds fail with the following error:
drivers/net/tsec.c:641:24: error: 'tsec_get_interface' defined but not used [-Werror=unused-function]
  641 | static phy_interface_t tsec_get_interface(struct tsec_private *priv)

Fix that.

Signed-off-by: Ramon Fried <rfried.dev@gmail.com>
1 file changed