serial: sh-sci: Add device tree support for r8a7{778,740,3a4} and sh73a0

Simply document new compat strings.
There appears to be no need for a driver updates.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/renesas,sci-serial.txt

@@ -4,6 +4,13 @@ Required properties:
 
   - compatible: Must contain one of the following:
 
+    - "renesas,scifa-sh73a0" for SH73A0 (SH-Mobile AG5) SCIFA compatible UART.
+    - "renesas,scifb-sh73a0" for SH73A0 (SH-Mobile AG5) SCIFB compatible UART.
+    - "renesas,scifa-r8a73a4" for R8A73A4 (R-Mobile APE6) SCIFA compatible UART.
+    - "renesas,scifb-r8a73a4" for R8A73A4 (R-Mobile APE6) SCIFB compatible UART.
+    - "renesas,scifa-r8a7740" for R8A7740 (R-Mobile A1) SCIFA compatible UART.
+    - "renesas,scifb-r8a7740" for R8A7740 (R-Mobile A1) SCIFB compatible UART.
+    - "renesas,scif-r8a7778" for R8A7778 (R-Car M1) SCIF compatible UART.
     - "renesas,scif-r8a7779" for R8A7779 (R-Car H1) SCIF compatible UART.
     - "renesas,scif-r8a7790" for R8A7790 (R-Car H2) SCIF compatible UART.
     - "renesas,scifa-r8a7790" for R8A7790 (R-Car H2) SCIFA compatible UART.