arm: dts: k3: binman: Fix DM firmware selection

arm: dts: k3: binman: Fix DM firmware selection

Just like TF-A and OP-TEE, the documentation states a custom path for DM
can be provided at build time by setting TI_DM. This should then set
ti-dm-path which updates ti-dm node filenames in binman.

Two issues prevent this from functioning for most K3 boards. One is when
then DM firmware name is inside a blob-ext node instead of a ti-dm node.

The second is when the filename in the ti-dm node is a pointer to a
blob-ext node. In this case even though the filename is updated, the
filename in the blob-ext is not, so build can fail if the default
file in the blob-ext cannot be found, even if the updated ti-dm file
does exist.

Fix both of these for all K3 by removing any indirect ti-dm nodes and
making sure all DM nodes are labeled with "ti-dm".

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Bryan Brattlof <bb@ti.com>
Reviewed-by: Neha Malcom Francis <n-francis@ti.com>