eth: mcux: Fix proper handling of the 'local-mac-address' property

After the change SHA1: 3498d437 the
local-mac-address property is no longer parsed correctly when it is
defined in the '&enet` DTS node on k6x SoCs (e.g. frdm_k64f and
ip_k66f).

The problem is with value to which the
NODE_HAS_VALID_MAC_ADDR(DT_DRV_INST(n)) macro is resolved.

If the 'local-mac-address' is present it returns
'(!((0 == 0) && (0 == 0) && (18 == 0) && (19 == 0) && (0 == 0) && \
 (16 == 0)))' [*], otherwise it is 0.

As COND_CODE_{01} only accepts 0 or 1 as its first argument, it all
worked until the 'local-mac-address' was not defined. When present
the first argument to COND_CODE_{01} macro was [*] and it caused
build break.

Fixes issue: #30354
https://github.com/zephyrproject-rtos/zephyr/issues/30354



Signed-off-by: Lukasz Majewski <lukma@denx.de>