clk: max77686: Refactor successful exit of probe function

The function can simply return 0, without jumping to a separate label,
which does exactly the same. This patch does not introduce any
functional change, just a clean-up.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>