ARM: dts: exynos: Correct whitespace and indentation issues

Remove double space after '=' and fix indentation in Exynos3250,
Exynos4210 and Exynos4412 boards.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200830135200.24304-33-krzk@kernel.org