ARM: dts: Build all keystone dt blobs
ARM: dts: Build all keystone dt blobs

Now we have additional two SOC/boards supported, so add
make file rule so that all device tree blobs can be build
for keystone with 'make dtbs'.

Signed-off-by: Santosh Shilimkar <5b4d8dc9ea337fff5fd1729321eda9873ade0b09@ti.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs