board: ti: am62ax: Add C7x resource allocation entries to board config

Update am62ax rm-cfg with allocation entries for C7x core. Following
updates are added for C7x:
- Share split BCDMA tx and rx channels between DM R5 and C7x
- Share rings for split BCDMA tx and rx channels between DM R5 and C7x
- Add Global events and Virtual interrupts for C7x

Signed-off-by: Vishal Mahaveer <vishalm@ti.com>