rtc: meson: simplify the return expression of meson_vrtc_probe

Simplify the return expression.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200919100856.1639319-1-liushixin2@huawei.com