Revert "drivers: display: elcdif: Modify interrupt enablement"

This reverts commit 20689765.

We must keep the frame completion interrupt disabled until we send a new
frame to the eLCDIF, as the frame completion interrupt fires at each
vertical blank interval. If we keep it enabled, then the semaphore we
use to indicate the frame has been loaded by the eLCDIF will be posted
to when we do not have a frame queued, and calls to `display_write` will
return before the eLCDIF has actually loaded the new framebuffer.

Fixes #80590

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>