dt-bindings: dma: ti: k3-pktdma: Describe cfg register regions

Packet DMA (PKTDMA) module on K3 SoCs have ring cfg, TX and RX channel
cfg and RX flow cfg register regions which are usually configured by a
Device Management firmware. But certain entities such as bootloader
(like U-Boot) may have to access them directly. Describe this region in
the binding documentation for completeness of module description.

Keep the binding compatible with existing DTS files by requiring first
four regions to be present at least.

Signed-off-by: Vignesh Raghavendra <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/dma/ti/k3-pktdma.yaml

···
       The second cell is the ASEL value for the channel
 
   reg:
+    minItems: 4
     items:
       - description: Packet DMA Control /Status Registers region
       - description: RX Channel Realtime Registers region
       - description: TX Channel Realtime Registers region
       - description: Ring Realtime Registers region
+      - description: Ring Configuration Registers region
+      - description: TX Configuration Registers region
+      - description: RX Configuration Registers region
+      - description: RX Flow Configuration Registers region
 
   reg-names:
+    minItems: 4
     items:
       - const: gcfg
       - const: rchanrt
       - const: tchanrt
       - const: ringrt
+      - const: ring
+      - const: tchan
+      - const: rchan
+      - const: rflow
 
   msi-parent: true
 
···
                 reg = <0x0 0x485c0000 0x0 0x100>,
                       <0x0 0x4a800000 0x0 0x20000>,
                       <0x0 0x4aa00000 0x0 0x40000>,
-                      <0x0 0x4b800000 0x0 0x400000>;
-                reg-names = "gcfg", "rchanrt", "tchanrt", "ringrt";
+                      <0x0 0x4b800000 0x0 0x400000>,
+                      <0x0 0x485e0000 0x0 0x20000>,
+                      <0x0 0x484a0000 0x0 0x4000>,
+                      <0x0 0x484c0000 0x0 0x2000>,
+                      <0x0 0x48430000 0x0 0x4000>;
+                reg-names = "gcfg", "rchanrt", "tchanrt", "ringrt",
+                            "ring", "tchan", "rchan", "rflow";
+
                 msi-parent = <&inta_main_dmss>;
                 #dma-cells = <2>;