clk: Combine DT binding doc for max77686 and max77802

The clock IP used on the Maxim PMICs max77686 and max77802 are
same. The configuration of clock register is also same except
the number of clocks.

Define the common DT binding file for the clocks of Maxim PMICs
MAX77686 and MAX77802. For this, remove the separate DT binding
document file for maxim,max77802 and move all information to
maxim,max77686 DT binding document.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
CC: Krzysztof Kozlowski <k.kozlowski@samsung.com>
CC: Javier Martinez Canillas <javier@dowhile0.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>