spi: sh-msiof: Add support for SH-Mobile AG5

MSIOF in SH-Mobile AG5 (sh73a0) is handled fine by the existing driver.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/sh-msiof.txt

@@ -10,6 +10,7 @@ Required properties:
 			 "renesas,msiof-r8a7792" (R-Car V2H)
 			 "renesas,msiof-r8a7793" (R-Car M2-N)
 			 "renesas,msiof-r8a7794" (R-Car E2)
+			 "renesas,msiof-sh73a0" (SH-Mobile AG5)
 - reg                  : A list of offsets and lengths of the register sets for
 			 the device.
 			 If only one register set is present, it is to be used