dma: ti: k3-psil-am654: Drop unused PSIL EP static data

ICSSG Ethernet driver uses two src threads per port (one per slice).
Similarly CPSW uses one src thread.

Drop PSIL EP static data for other src threads in order to reduce
R5 SPL footprint. This makes AM65x board bootable again.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>