drivers: eth_enc424j600: explicitly disable INTIE after reset

After system reset (SETETHRST) interrupt enable register (EIE)
has the default value 0x8010 and global interrupt enable flag (INTIE)
is set. This is not desired and the INTIE flag should be set only at
the end of the initialization.

Disable INTIE flag and set desired interrupts sources in
a single write command just right after system reset.

Resolves: #35091

Reported-by: Jamie McCrae <jamie.mccrae@lairdconnect.com>
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>