ARM: shmobile: r8a7791 dtsi: Fix typo in msiof2 clock output name

Introduced in commit cded80f8 ("ARM:
shmobile: r8a7791: Add MSIOF clocks in device tree").

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>