ARM: shmobile: defconfig: Enable RZ/A watchdog support

Enable support for the RZ/A watchdog timer, which is used on RZ/A1H and
RZ/A2M boards.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200624131931.3686-5-geert+renesas@glider.be

arch/arm/configs/shmobile_defconfig

@@ -101,6 +101,7 @@ CONFIG_RCAR_THERMAL=y
 CONFIG_WATCHDOG=y
 CONFIG_DA9063_WATCHDOG=y
 CONFIG_RENESAS_WDT=y
+CONFIG_RENESAS_RZAWDT=y
 CONFIG_MFD_AS3711=y
 CONFIG_MFD_DA9063=y
 CONFIG_REGULATOR_FIXED_VOLTAGE=y