ipc-lld: add AM65xx IPC echo_test firmware binaries
ipc-lld: add AM65xx IPC echo_test firmware binaries

Use IPC/LLD based IPC echo test binaries as an
alternative for AM65X Linux IPC testing.
Updated location of J721E firmware binaries as well,
with latest IPC/LLD commit.

Signed-off-by: Jonathan Bergsagel <39169b6fa45decaae183c68b42ef6fc30cc3a498@ti.com>
Signed-off-by: Denys Dmytriyenko <d29de71aea38aad3a87d486929cb0aad173ae612@ti.com>

rcn-ee/meta-ti,rcn-ee/meta-ti,rcn-ee/meta-ti,rcn-ee/meta-ti