binman: etype: dm: Add entry type for TI DM

K3 devices introduces the concept of centralized power, resource and
security management to System Firmware. This is to overcome challenges
by the traditional approach that implements system control functions on
each of the processing units.

The software interface for System Firmware is split into TIFS and DM. DM
(Device Manager) is responsible for resource and power management from
secure and non-secure hosts. This additional binary is necessary for
specific platforms' ROM boot images and is to be packaged into tispl.bin

Add an entry for DM. The entry can be used for the packaging of
tispl.bin by binman along with ATF and TEE.

Signed-off-by: Neha Malcom Francis <n-francis@ti.com>
Reviewed-by: Andrew Davis <afd@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>