drivers: nxp_enet: Do clock init from zephyr

Need to do the ENET module-level clock initialization from zephyr
instead of MCUX HAL, because now there are multiple zephyr drivers with
different init priorities that rely on the module being clocked. MDIO
must be initialized before the ENET MAC, and the MAC driver currently
calls ENET_Init from the HAL to initialize the clock, but MDIO needs the
module clock enabled first on some platforms. So replace the MAC init
with ENET_Up from the HAL, which doesn't include clock init, then do
clock init from a higher priority sys init based on the parent
compatible.

Also, add support for enet clock ungating with clock_control_on on ccm
driver do this with current platforms supported.

Signed-off-by: Declan Snyder <declan.snyder@nxp.com>