arm64: dts: ti: k3-j721s2-main: add wave5 video encoder/decoder node

Add the Chips and Media wave521cl video decoder/encoder node on J721S2.

This functional block also requires an SRAM buffer as a bandwidth saving
temporary store so we need to add a carve out of 126K for this as
specified in the documentation.

Signed-off-by: Darren Etheridge <detheridge@ti.com>