clk: max77686: Avoid double free at remove time

The clk_lookup entry is dropped at remove time by a call to
clkdev_drop(). That function frees the entry, which is also freed by the
driver core as it has been allocated through devm_kzalloc(). This
results in a double free.

Use kzalloc() instead of devm_kzalloc() to fix this.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>