dt-bindings: crypto: inside-secure,safexcel: Allow dma-coherent

Some platforms like Marvell are cache coherent, so allow the
"dma-coherent" property.

Signed-off-by: Rob Herring (Arm) <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

Documentation/devicetree/bindings/crypto/inside-secure,safexcel.yaml

···
       - const: core
       - const: reg
 
+  dma-coherent: true
+
 required:
   - reg
   - interrupts