clk: samsung: exynos4: Remove checks for DT node

Exynos 4 supports only DT based bootup, so non-DT cases does not need to
be handled anymore.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>