drivers: dma: dma_nxp_edma: switch to using DT_INST_IRQN_BY_IDX

After #63289, multi-level interrupts are now encoded using
macro magic. This means that using the generic DT_INST_IRQ_BY_IDX()
to fetch the INTID is no longer an option as the queried INTID
will be the one specified through the node's `interrupts`
properties. To fix this, switch to using DT_INST_IRQN_BY_IDX()
which will return the correctly encoded INTID.

Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>