clk: max77686: fix number of clocks setup for clk_hw based registration

The commit 9b4cac33 ("clk: max77686: Migrate to clk_hw based OF and
registration APIs") converted the driver to use the new provider API to
register clocks using clk_hw.

But unfortunately, in the conversion it missed to set the num_clks value
which lead to the following error when trying to register a clk provider:

[    1.963782] of_clk_max77686_get: invalid index 0
[    1.967460] ERROR: could not get clock /rtc@10070000:rtc_src(1)
[    1.973638] s3c-rtc 10070000.rtc: failed to find rtc source clock

Fix it by correctly set the max77686_clk_driver_data num_clks member.

Fixes: 9b4cac33

 ("clk: max77686: Migrate to clk_hw based OF and registration APIs")
Reported-by: Markus Reichl <m.reichl@fivetechno.de>
Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Markus Reichl <m.reichl@fivetechno.de>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>