dma: ti: k3-udma: Fix rflow reservation for PKTDMA

Driver has a bug in that it uses rflow_in_use bitmap when setting up free rflow range
from TISCI but use rflow_map for reservation in __udma_reserve_rflow()

Fix this by dropping rflow_in_use bitmap array and use rflow_map for
PKTDMA. BCDMA does not need rflow_in_use either.

This fixes CPSW3g not able to get DMA channels at R5 SPL on AM64x

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