ARM: dts: r7s72100: Correct watchdog timer interrupt type

According to table 7.3 ("List of Interrupt IDs") in the RZ/A1H Hardware
User's Manual rev. 3.00, the watchdog timer interrupt is a level
interrupt.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>