ARM: dts: exynos: use generic name for max77693 motor in Midas

Use a generic name for the max77693 motor driver in Exynos4412 Midas
boards to align with Devicetree specification naming convention.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201105184506.215648-3-krzk@kernel.org