arm64: dts: renesas: r8a77970: Fix PWM3

arm64: dts: renesas: r8a77970: Fix PWM3

The pwm3 was incorrectly added with a compatible reference to the
renesas,pwm-r8a7790 (H2) due to a single characther ommision.

Fix the compatible string.

Fixes: de625477c632 ("arm64: dts: renesas: r8a779{7|8}0: add PWM support")
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Link: https://lore.kernel.org/r/20190912103143.985-1-kieran.bingham+renesas@ideasonboard.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>