clk: max77686: Fix return value checking for devm_kzalloc

devm_kzalloc returns NULL on failure.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

diff --cc drivers/clk/clk-max77686.c
Simple merge